Leiden Institute of Chemistry Leiden University

November8,2017

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LeidenInstituteofChemistry

2017


LeidenUniversity

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November8,2017

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DutchSPMDay2017

Organizedby:

LeidenUniversity

IreneGroot

Secretary:JoséDijkzeul

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Program

9.00-9.25:arrival+coffee9.25-9:30:opening

9.30-10.20:invitedtalkMarkusHeyde,FritzHaberInstituteBerlin,Germany"LookingintotheStructureofGlassbyDesigningaNew2DMaterial"10.20-10.40:contributedtalkSamuelLesko,Bruker"Highresolutionelectricalcharacterizationinliquidbyconductivenanoelectrodeprobes"10.40-11.00:contributedtalkMaartenLeeuwenhoek,LeidenUniversity/TUDelft"NanofabricatedSTMdouble-tipsforprobingquantummaterials"

11.00-11.30:coffee/teabreak

11.30-11.50:contributedtalkXinDeng,LeidenUniversity"InsituobservationofPtelectrodebyelectrochemicalAFMinsulfuricacidunderpotentialcyclingconditions"11.50-12.10:contributedtalkPantelisBampoulis,TUTwente"Pressureinducedmeltingofnanoconfinedice"12.10-12.30:contributedtalkMarlouSlot,UtrechtUniversity"(Below)2D:realizingelectronicstructuresonaCu(111)surfacebyatomicmanipulation"

12.30-14.00:lunch,exhibition,postersession

14.00-14.50:invitedtalkVolkerRose,ArgonneNationalLaboratory,USA"SynchrotronX-rayScanningTunnelingMicroscopy:ANovelApproachfortheNanoscaleCharacterizationofMaterialswithChemicalandMagneticContrast"14.50-15.10:contributedtalkBayTran,RUGroningen"On-surfaceformationofcumulenebydehalogenativehomocouplingofalkenylgem-dibromides"15.10-15.30:contributedtalkLeonJacobse,LeidenUniversity"CorrelationofsurfacesiteformationtonanoislandgrowthintheelectrochemicalrougheningofPt(111)"

15.30-16.00:coffee/teabreak

16.00-16.20:contributedtalkAlexanderVolodin,KULeuven"Stressdependenceofthesuspendedgrapheneworkfunction:VacuumKelvinprobeforcemicroscopyanddensityfunctionaltheory"16.20-16.40:contributedtalkOlegKurnosikov,TUEindhoven"FunctionalizationofcleavedprobesforSTMandAFM"16.40-17.00:contributedtalkMartindeWit,LeidenUniversity"Quantifyingspin-induceddissipationusingM(R)FM"

17.00:drinkssponsoredbyBruker(“BrukerBorrel”)

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9:30 MarkusHeyde,FritzHaberInstituteBerlin

LookingintotheStructureofGlassbyDesigningaNew2DMaterialMarkusHeyde,Fritz-Haber-InstitutderMax-Planck-Gesellschaft,Faradayweg4-6,14195

Berlin,Germany,Electronicmail:[email protected] the structure of amorphous materials used to be challenging due to thecomplexityofthismaterialclass.HereIwouldliketoreviewstructuralstudiesofbulkandtwo-dimensionalamorphoussilica, focusingontherecentdiscoveryanew2Damorphousmaterial. For the first time a clear image of an amorphous network structure has beenobtainedwhichallowedforthederivationofatomicsitesandadetailedanalysisfromrealspacecoordinatesbyusingscanningtunnelingandatomicforcemicroscopy.Iwilldiscussthebenefitsofthesemeasurementsonthenewlydevelopedthinsilicabilayerfilmsystemandconsidercomparisonsbetweentwo-dimensionalstructuresandtheirthree-dimensionalbulksilicacounterparts.Recentexperimentswhichestablish2Damorphoussilicaasacandidateinsulatingmaterialfortwo-dimensionalnanoelectronicswillalsobediscussed.Furthermore,Iwouldliketoprovideyouasneakpreviewintothelatestresultspointingtowardsanotheramorphousoxidefilmsystem.

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10.20 SamuelLesko,Bruker

Highresolutionelectricalcharacterizationinliquidbyconductivenanoelectrodeprobes

SamuelLesko,PeterDeWolf,RakeshPoddar,andZhuangqunHuang*BrukerNanoSurfaces,112RobinHillRoad,Goleta,California,CA,93117,USA

*CorrespondingAuthor:[email protected] and catalytic researches are nowadays topics of importancewhere reactivity andelectricalpropertiesheterogeneityofmaterialsonthenanoscalehaveasignificantimpactonmacroscopic performance. The differences in structural, mechanical, electrical, and/orelectrochemicalpropertieslocallyalltogetheraccountforthisreactivityvariation.Therefore,approachescapableofsimultaneouslycapturingcorrelatedmultidimensionalinformationonthe nanoscale in liquid media are highly desire to perform in situ, in vivo, non-invasivecharacterizationduetothenaturesofthesamples.Whileclassicscanningelectrochemicalmicroscopy(SECM)usingmicro-electrodesisknownapproachforstudyinglocalelectrochemistry,itsufferschallengesonthepositioncontrolofthe tip-sample distance, which is essential for obtaining accurate electrochemicalinformation.Inaddition,thespatialresolvingpowerisgenerallylowanddifficulttoachievesub μm resolution. Likewise, standard AFM based techniques in air for electricalcharacterization such as capacitance, conductivity, surface potential cannot apply inconductiveliquidsduetostraightcurrentleakage.Furthermore,samples,suchasbiologicalorenergymaterialsareoftenhighlysoftandfragilewhichposesanothergrandchallengeforAFM-basedimagingusingclassiccontactmode.Recently,wehavedevelopedbatch-fabricated,high-qualityandrobustnanoelectrodeprobesfullyinsulatedfromsolutionexceptionmadefortipapexwhichexposesPt-coatedconductivetip ~200 nm height with diameter of ~50 nm. These probes pass > 10 hours continuouselectrochemicaltestingandfeaturetheeaseofuse.TheseprobesareusedincombinationwithPeakForceTapping(PFT)modewhereprobeissinusoidallymodulatedatoff-resonance,lowfrequency,withadefinedimagingforceaslowas20pN.Thisenablesinsitu,invivo,non-invasive,stableimagingforchallengingfragileandsoftsamples.PFTisessentiallybasedonfastforcecurveacquisitionandanalysis.ItnaturallyallowsquantitativemechanicalmappingsatnormalAFMscanrate.Combinationofhigh-qualitynanolectrodesprobeswithPFT,allowsus to simultaneously capture multidimensional information in the electrochemicalenvironmentat<100nmspatialresolution,includingtopographic,conductivity,mechanical,andelectrochemicalproperties.Inaddition,thenanoelectrodeprobebydesignalsoenablesallothernanoelectricmeasurementsinliquidasitisfullyinsulatedexceptforthetip.1,2

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This talk showcases a variety of applications examples using nanolectrodes, includingcatalysis,surfacedefectsonlamellar,patternednanostructuredelectrodes,etc.Associatedspectroscopymappingwillbeshowntoillustratepowerofsuchanapproach.SomeexamplesaboutnanoelectricmeasurementssuchasKelvinprobeandPiezoResponseinliquidarealsopresented.Thesecasesdemonstratetheversatilityandpotentialnewcapabilities throughthosenanoelectrodesthatarewellsuitedfortoday’shighly-multidisciplinaryresearch.

Figure1.Left:SEMimagesoftheprobe.TheprobeisfullyinsulatedwithonlythePt-coatedtipapexexposed.Right:Exampleofelectricalcharacterizationinliquid.Oncenter:batteryelectrodeinDMCwithcontactcurrentmapping inPeakForceTapping.On left,meshofSiliconNitridewithopeningmadeofPlatinum ismeasuredbyFrequencyModulationbasedKelvinprobemicroscopy inmilli-Qwater.References:1Nellistetal.,Nanotechnology,2017,28,095711.2Huangetal.,MicroscopyToday,2016,24,18.

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10.40 MaartenLeeuwenhoek,LeidenUniversity/TUDelft

NanofabricatedSTMdouble-tipsforprobingquantummaterialsMaartenLeeuwenhoek1,2,RichardNorte1,KoenM.Bastiaans2,IreneBattisti2,YaroslavM.

Blanter1,JanZaanen2,MilanP.Allan2andSimonGröblacher11:KavliInstituteofNanoscience,DelftUniversityofTechnology,2628CJDelft,The

Netherlands2:LeidenInstituteofPhysics,LeidenUniversity,NielsBohrweg2,2333CALeiden,The

Netherlands

Here, we report on the design and fabrication of a new type of smart tip for ScanningTunneling Microscopy (STM). By fully integrating a metallic tip onto a silicon chip usingmodernmicro-machiningandnanofabricationtechniquesweshowthepossibilityofdevicebasedSTMtips.Contrarytotraditionaletched/grindedwiretips,thesecanbeintegratedinlithographicallydefinedelectricalandphotoniccircuits,aswellaswithmechanicalsystems.We aim at creating two-probe deviceswith a tip to tip spacing below ~50-100 nm. Suchdoubletipscouldnotonlymeasurethelocaldensityofstatesatthetwoindividualtipswithatomicresolution,butalsothecurrentsentthroughonetipandcollectedbytheother.Thiswouldallowustomeasureandmapthetwopointpropagatoroftheelectrons,providingnewinformationonthetransportofcorrelatedelectronsattheatomicscale.

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11.30 XinDeng,LeidenUniversity

InsituobservationofPtelectrodebyelectrochemicalAFMinsulfuricacid

underpotentialcyclingconditions

XinDeng,FedericaGalli,MarcT.M.Koper

UnderstandingtheelectrochemicalbehaviorofPtatsolid/liquid interface isofsignificantimportancetothedevelopmentofefficientelectrochemicaldevices,suchasfuelcellsandwaterelectrolyzers.Inthiswork,theevolutionofthesurfacemorphologyofapolycrystallineplatinum under potential cycling condition was investigated by EC-AFM. After 50 cyclesbetween0.05-1.8Vin0.1MH2SO4,thePtsurfaceiscoarsenedandnanoparticlesofseveralnanometersappearonthesurface.Thecriticalupperandlowerpotentialfornanoparticlesformationisfoundtobe1.8and0.8V,respectively.TheinsituAFMobservationcoupledwithCV reveals the periodic disappearance and reappearance of the nanoparticles, based onwhich, the nanoparticles are attributed to be Pt nanoparticles and a model for thenanoparticles formation is proposed. While the formation of a thick oxide layer is theprerequisite,thereductionprocessisfoundtohaveastronginfluenceonPtnanoparticlesformation as well. This investigation provides the visualization of Pt surface underelectrochemical control in a large potential window, which enables a more intuitiveunderstandingofthePtredoxprocess.

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11.50 PantelisBampoulis,TUTwente

Pressureinducedmeltingofnanoconfinedice

PantelisBampoulis,TUTwenteThestatesofaggregationofconfinedwaterarehighlyimportantandofgreatfundamentalinterestinsurfacechemistry,lifeandenvironmentalsciences.Duetolimitedexperimentalaccessacoherentunderstandingofthephasebehaviorandtheoccurringphasetransitionsof interfacial ice is still lacking. Using scanning probe techniques,we show that, at roomtemperature, ice confined between graphene and muscovite mica undergoes a phasetransition to a quasi-liquid phase at a critical applied pressure of 6GPa. The transition iscompletely reversible, that is, refreezing occurs when the applied pressure is lifted. Ourfindings form a paradigm of the classical phenomenon of regelation decoupled fromenvironmentalthermaleffects.Thecriticalpressuretomelttheicecrystalsislowerathighertemperatureandthelatentheatoffusion(0.15eV/H2O)ismorethantwotimeslargerthanthecorrespondingthreedimensionalvalueatambientconditions.

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12.10 MarlouSlot,UtrechtUniversity(Below)2D:realizingelectronicstructuresonaCu(111)surfacebyatomic

manipulation

M.R.Slot1,S.N.Kempkes2,T.S.Gardenier1,P.H.Jacobse1,G.C.P.vanMiert2,S.J.M.Zevenhuizen1,C.MoraisSmith2,D.Vanmaekelbergh1andI.Swart1

1DebyeInstituteforNanomaterialsScience,UtrechtUniversity,theNetherlands2InstituteforTheoreticalPhysics,UtrechtUniversity,theNetherlands

Geometryanddimensionalityaredecisivefactorsfortheelectronicpropertiesofmaterials.Anexample is the2-Dhoneycomb latticeofgraphene,giving rise toDiraccones inwhichchargecarriersbehaveaseffectivelymasslessparticles.Apossibleroutetocreatenovelflatstructures inacontrolledmanner isbyconfiningthesurfacestateelectronsofCu(111)byaccuratepositioningof adsorbedCOmolecules [1]. Employing this strategy,we show therealizationofaLieblattice[2]:a2Dsquare-depletedlattice,whichischaracterizedbyabandstructure featuring Dirac cones intersected by a flat band. Using scanning tunnellingmicroscopy, spectroscopy and wavefunction mapping, we confirm the predictedcharacteristicelectronicstructureoftheLieblattice.Athigherenergies,wefindstatesthatoriginatefromtheartificialp-orbitalsoftheelectroniclattice.Moreover,wemovebeyondthe well-studied integer dimensions. Fractional dimensions could open a new range ofpossibilitiesforelectronicnanosystems.Here,werealizeandcharacterizeaSierpińskitrianglefractalwithdimension1.58.Wefindthat the fractalityof thisquantumfractal isnotonlyreflectedinthegeometryandenergylevels,butalsointhewavefunctions,whicharefractalthemselves. The experimental findings were reproduced by muffin-tin and tight-bindingcalculations.1.K.K.Gomesetal.,Nature483,306–310(2012)2.M.R.Slotetal.,NaturePhysics13,672-676(2017)

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14.00 VolkerRose,ArgonneNationalLaboratory,USA

SynchrotronX-rayScanningTunnelingMicroscopy:ANovelApproachfortheNanoscaleCharacterizationofMaterialswith

ChemicalandMagneticContrast

VolkerRoseX-rayScienceDivision&CenterforNanoscaleMaterials

ArgonneNationalLaboratory9700SouthCassAvenue

Argonne,IL60439-4800,USAAdj.Professor,Physics&AstronomyDepartment

OhioUniversity,Athens,OH45701,USA

The real-space observation of chemistry and magnetic structure using scanning probemicroscopy(SPM)methodsorsynchrotron-basedx-raymicroscopy(XM)continuestohaveatremendous impactonourunderstandingoffunctionalmaterials.However,althoughSPMmethodsprovidehighspatialresolution,theytypicallylackdirectchemicalcontrastandtheabilitytoquantifymagneticmoments.Ontheotherhand,XMcanprovidechemicalaswellasmagnetic sensitivity, but the spatial resolution is inferior. In order to overcome theselimitations, various groups have developed a new technique that combines synchrotronradiationwiththehighspatialresolutionofscanningtunnelingmicroscopy(STM).Thegoalistocombinethespinsensitivityandchemicalcontrastofsynchrotronx-rayswiththelocalityofSTM.Recently,substantialprogresswasmadeonArgonne’ssynchrotronx-rayscanningtunnelingmicroscopy (SX-STM) project. In particular, we demonstrated the power of SX-STM forelemental characterization and topography of individual Ni and Co nano-islands at 2 nmlateral resolutionwith single atomheight sensitivity [1,2], tested newprobe tip conceptsbasedoncarbonnanotubes[3]andmultilayertips[4],anddemonstratedx-rayimagingofnanoscalemagneticdomainsofanironthin-filmbyx-raymagneticcirculardichroism(XMCD)contrast[5].Furthersubstantialadvancesareexpectedusingthenewlowtemperature(LT)SX-STM system, which has been developed over the last 3 years and is currently undercommissioning.Tofullyexploitthespecialcapabilitiesofthenewmicroscope,XTIP,adedicatedbeamlineforSX-STMisunderconstructionattheAdvancedPhotonSource.Tomeetthescientificobjectiveofthenanoscienceandnanomagnetismcommunitiesmosteffectively,wearegoingtobuildasoftx-raybeamlinewithfullpolarizationcontroloperatingoverthe500-2000eVenergy

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range. The dedicated XTIP beamline will provide researchers access to a one-of-a-kindinstrument. Among the potential breakthroughs are “designer” materials created fromcontrolled assemblies of atoms and molecules, and the emergence of entirely newphenomenainchemistryandphysics.Thisworkwas fundedbytheOfficeofScienceEarlyCareerResearchProgramthroughtheDivisionofScientificUserFacilities,OfficeofBasicEnergySciencesoftheU.S.DepartmentofEnergythroughGrantSC70705.ThisworkwasperformedattheAdvancedPhotonSourceandtheCenterforNanoscaleMaterials,aU.S.DepartmentofEnergyOfficeofScienceUserFacilityunderContractNo.DE-AC02-06CH11357.References:[1] N.Shiratoetal.,NanoLetters14,6499(2014).[2] H.Kerselletal.,Appl.Phys.Lett.,inprint(2017).[3] H.Yanetal.,J.Nanomaterials2015,492657(2015).[4] M.Cummingsetal.,J.Appl.Phys.121,015305(2017).[5] A.DiLulloetal.,J.SynchrotronRad.23,574(2016).

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14.50 BayTran,RUGroningen

On-surfaceformationofcumulenebydehalogenativehomocouplingofalkenylgem-dibromides

B.Tran,1Q.Sun,2L.Cai,2H.Ma,2X.Yu,2C.Yuan,2M.Stöhr,1andW.Xu21ZernikeInstituteforAdvancedMaterials,UniversityofGroningen,Groningen,Netherlands

2InterdisciplinaryMaterialsResearchCenter,TongjiUniversity,Shanghai,China

Recently,on-surfacesynthesisbasedontheuseofcovalentlinkinghasofferedanexcellentplatform to construct novel 1D and 2D carbon-based materials. This new approach hasreceivedconstantlyincreasingscientificattentionbecauseofitsadvantagescomparedtoitscounterpart solution-based synthesis for building durable, controllable nanostructures forfutureelectronicdevices.ThemostfrequentlyusedreactionisUllmann-typecouplingwhichinvolvesthethermallyinduceddehalogenationofpre-definedC-Xgroups(X=halogenatom)fortheformationofC-Cbonds.Sofar,allemployedhalideprecursorshaveonlyonehalogenattached to a carbon atom. Therefore, to extend our fundamental understandings of on-surfaceC−Ccouplingreactionsitisparticularinteresttostudytheeffectofintroducingmorethan one halogen atom to a carbon atom with the aim of producing multiple unpairedelectrons.In this work, we successfully fabricated cumulene products on a Au(111) surface viadehalogenativehomocoupling reactionsby introducinganalkenylgem-dibromide [1].Thereactionproductsandpathwayswereunambiguouslycharacterizedbythecombinationofhigh-resolution scanning tunneling microscopy (STM) and non-contact atomic forcemicroscopy(nc-AFM)measurementstogetherwithstate-of-the-artdensityfunctionaltheory(DFT) calculations. This study further supplements the database of on-surface synthesisstrategies,andimportantly,itprovidesafacilemannerforincorporationofmorecomplicatedcarbonscaffoldingsintosurfacenanostructures.[1]Q.Sun,B.Tran,etal.,Angew.Chem.Int.Ed.56,12165–12169(2017).

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15.10 LeonJacobse,LeidenUniversity

CorrelationofsurfacesiteformationtonanoislandgrowthintheelectrochemicalrougheningofPt(111)

LeonJacobse1,Yi-FanHuang1,MarcT.M.Koper1,andMarcelJ.Rost21LeidenInstituteofChemistry,LeidenUniversity,Leiden,TheNetherlands

2Huygens-KamerlinghOnnesLaboratory,LeidenUniversity,Leiden,TheNetherlandsPlatinum plays a central role in a wide variety of electrochemical devices. Electrodedegradation, especially under oxidizing conditions, forms an important barrier for thewidespreadapplicationof suchdevices.Although it isknownthat repeatedoxidationandreductionofplatinumelectrodesresultsinirreversiblesurfacestructurechanges,overthirtyyearsofresearchdidnotyetyieldtoaconclusivedescriptionofthisprocessontheatomiclevel;notevenforwell-definedsinglecrystalsurfaces.Using a special EC-STM, which is capable of measuring the electrochemical signalssimultaneously during imaging in operando, we directly correlate, for the first time, theevolution of the electrochemical (hydrogen desorption) signal of Pt(111) to the observedroughening of the surface. In the later stages, we find a strong correlation between theevolutionoftheroughnessandtheabsorptionpeaksclearlyindicatingthateachcreatedstepcontributesequallystrongtotheadsorptionsignalaswellastotheroughness.However,andfully surprising, in the early stages step edges are created that do not contribute to theelectrochemicalsignal.TheseresultspresentnotonlyanimportantstepforwardinunderstandingtheatomicscaleprocessoftheelectrochemicalrougheningofPt(111),butalsoprovidevaluableinsightinthedegradationofindustriallyrelevantplatinumnanoparticles,asalargepartoftheirsurfaceisnaturallycomposedoutof{111}planes.

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16.00 AlexanderVolodin,KULeuven

Stressdependenceofthesuspendedgrapheneworkfunction:VacuumKelvinprobeforcemicroscopyanddensityfunctionaltheory

A.Volodin,1C.VanHaesendonck,1O.Leenaerts,2B.Partoens,2andF.M.Peeters2

1KULeuven,AfdelingVaste-stoffysicaenMagnetisme,Celestijnenlaan200D,BE-3001

Leuven,Belgium2UniversiteitAntwerpen,DepartementFysica,Groenenborgerlaan171,BE-2020Antwerpen,

BelgiumWe report on work function measurements on graphene, which is exfoliated over apredefined array of wells in silicon oxide, by Kelvin probe forcemicroscopy operating invacuum. The obtained graphene sealed microchambers can support large pressuredifferences, providing controllable stretching of the nearly impermeable graphenemembranes.These measurements allow detecting variations of the work function induced by themechanicalstressesinthesuspendedgraphenewheretheworkfunctionvarieslinearlywiththestrainandchangesby62±2meVfor1percentofstrain.Ourrelatedabinitiocalculationsresultinworkfunctionvariationlargerbyafactorof1.4thantheexperimentalvalue.The limiteddiscrepancybetweentheoryandexperimentcanbeaccountedforbyachargetransferfromtheunstrainedtothestrainedgrapheneregions.

A.Volodinetal.,Appl.Phys.Lett.110,193101(2017)

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16.20OlegKurnosikov,TUEindhoven

FunctionalizationofcleavedprobesforSTMandAFM

O.Kurnosikov,H.T.Ciftci,B.KoopmansAnalternativetypeofprobesforSTMortuningfork-basedAFMisproposed[1].Insteadofusingtraditionalneedle-liketipsmadefromametallicwire,weuseasharpedgeofacleavedinsulatingsubstratewhichinitiallywascoveredbyathinlayerofconductingmaterial.Thesharptipisformedattheintersectionoftwocleavinglines.TestingthecleavedtipsinSTMandAFMrevealstheresolutiondowntoatomicscale,thesameasforconvenientSTM/AFMtips.However,withourapproach,theplanarsubstratesfortipfabricationareverysuitableforaverysimpleandflexiblefunctionalizationoftheSTMandAFMtips,forexamplebyusingthe cleavable substrates with magnetic, superconducting or other specific layers for tipfabrication. Moreover, profiting from Electron Beam or Focused Ion Beam Lithography(EBL/FIB) we also were able to tailor themetallic layer to obtain two- or multi-terminalstructuresontheprobe.Theelectriccurrentacrossamicro-ornanostructureformednearthetipendcanmodulatethetip-sampleinteractionandcanbeusedeitherforaswitchablesensingorasamplemanipulationonthenanoscale.Asanexamplewepresentaprototypeofmagnetically switchable or adaptiveMFMprobes. The current sent through a 100 nmconstrictionnearthetipendcangeneratealocalizedmagneticfieldofupto20mTwhichissufficient formagneticmanipulation. Inthesameway it isalsopossibletogenerateshortheatingpulsesforlocalmodificationofthesampleornano-printing.1.T.Siahaanetal.Nanotechnology,27,03LT01(2016)

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16.40 MartindeWit,LeidenUniversity

Quantifyingspin-induceddissipationusingM(R)FM

MartindeWit,GesaWelker,MarcdeVoogd,JelmerWagenaar,ArthurDenHaan,TjerkOosterkamp

Magnetic Resonance ForceMicroscopy is a technique that uses a very soft cantilever tomeasuretheforcesbetweenitsmagnetictipandthespinsinasample.Typically,MagneticResonanceprotocolsareusedtomanipulatethemagnetizationofthespinensemble,therebychangingthetip-sampleinteraction.However,wehaveutilizedtheextremeforcesensitivityofourMRFMsetuptomeasurethedensityandT1timesofparamagneticspinsinthenativeoxidelayerofsilicon,withoutsendingresonantpulses.Wealsodeterminedthedensityofthefreeelectronspinsassociatedwithnitrogendefectsindiamond.Toexpandthenumberofapplicationsofthistechnique,wearecurrentlyworkingonanewMRFMsetup,nicknamedtheEasy-MRFM. Itwill enablemeasurementsona larger varietyof samples since it isnolongernecessarytointegratethesampleunderinvestigationwiththechipthatgeneratestheoscillatingB1fieldandprovidesthedetectionofthemotionoftheforcesensor.

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PosterAbstracts

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Poster1

ImagingPulsedLaserDepositionoxidegrowthbyin-situAtomicForce

Microscopy

W.A.Wessels,T.R.J.Bollmann*,D.Post,G.Koster,andG.RijndersUniversityofTwente,InorganicMaterialsScience,MESA+InstituteforNanotechnology,P.O.

Box217,NL-7500AEEnschede,TheNetherlands*Correspondingauthor:[email protected]

Theperovskiteoxidesarea fascinatingclassofmaterials,due to theirwealth inavailablephysical properties, such as superconductivity, ferromagnetism, ferro- and dielectricity.Control on the growth of such (ultra)thin film structures is very beneficial as it leads tounanticipatedfunctionalproperties.However, to gain deep insight in the growth process, the current in-situ diagnostic tools(RHEED,SXRD,SE)alloperateinreciprocalspacemakinginterpretationnotstraightforwardandaveragingoverlargesurfaceareas.Inthisposter,wepresentthedevelopmentofasurfaceprobemicroscopy(SPM)techniquewithwhichweenablelocaltopographymeasurementsofthethinoxidefilmgrowthfrontinreal-spaceandatthenanometerscale.Wepresenttheconcept,specifications,designandperformanceofouratomicforcemicroscope(AFM)inapulsedlaserdeposition(PLD)vacuumsetup. The demonstrated performance on a typical perovskite oxide surfaces is of greatimportancenotonlyforthethinfilmoxidecommunity,butalsotowardsabroaderaudienceasitenablesmanymorefutureapplicationsformonitoringgrowthinprocessconditions.

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Poster2

PoorelectronicscreeninginlightlydopedMottinsulatorsobservedwithSTM

IreneBattistietal.,LeidenUniversity

The effectiveMott gapmeasured by scanning tunnelingmicroscopy in the lightly dopediridate (Sr1-xLax)2IrO4 differs greatly from values reported by photoemission and opticalexperiments.Here,weshowthatthisisaconsequenceofthepoorelectronicscreeningofthetip-inducedelectricfield,aneffectwellknownforsemiconductorsandcalledtip-inducedbandbending(TIBB).WedevelopamodelabletoretrievetheintrinsicMottgapfordopingconcentrationsx<4%,leadingtoavaluewhichisinroughagreementwithotherexperiments.Atdopingx≈5%we furtherobservecircular features in theconductance layers, indicatinghigherdensityof freecarriersandpresenceofa small concentrationofdonoratoms.Weillustrate the importance of considering the presence of TIBB in STM experiments oncorrelated-electron systems and discuss the similarities and differences between STMmeasurementsonsemiconductorsandlightlydopedMottinsulators.

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Poster3

Localcontrolofatomicvacanciestocreateartificialmaterials

F.E.Kalff*1,J.Girovsky1,D.CoffeyBlanco1,J.L.Lado2,E.Fahrenfort1,J.W.vanDam1,L.J.J.M.

Peters1,P.Schmitteckert4,F.Evers5,J.Fernández-Rossier2,3andA.F.Otte1

1DepartmentofQuantumNanoscience,DelftUniversityofTechnology,,Delft,TheNetherlands

2QuantaLab,InternationalIberianNanotechnologyLaboratory(INL),Braga,Portugal.3DepartamentodeFísicaAplicada,UniversidaddeAlicante,Alicante,Spain

4TheoretischePhysik,UniversitätWürzburg,Germany5TheoretischePhysik,UniversitätRegensburg,Germany

Large-scalemanipulation bymeans of scanning tunnelingmicroscopy (STM) of individualvacanciesinachlorinemonolayeronCu(100)isusedtoconstructone-andtwo-dimensionalstructuresofcoupledvacancies[1]invariousdensitiesandsizes,inordertoinvestigatetheirelectronicandspectroscopicproperties.Local scanning tunneling spectroscopy (STS) measurements reveal the emergence ofquasiparticlebands,evidencedbystandingBlochwaves,wherethenumberofnodesdependsontheenergyandthelatticestructure.Thissignifiesthatchangingthelatticepropertiesisawayoftuningthequasiparticledispersion,whichleadstodifferenteffectiveelectronmasses.Theexperimentaldatacanbeunderstoodintermsofatight-bindingmodelcombinedwithanadditionalbroadeningtermthatallowsanestimationofthecouplingtotheunderlyingsubstrate[2].1.Drostetal.,NaturePhysics13,668–671(2017)2.Girovskyetal.,SciPostPhys.2,020(2017)

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Poster4

SurfaceStructureDependentPhysisorptionofCO2

S.V.Auras1,R.G.Farber2,R.vanLent1,3,R.Spierenburg1,D.Bashlakov4,D.Killelea2,L.B.F.Juurlink1

1LeidenInstituteofChemistry,LeidenUniversity,

2LoyolaUniversityChicago,3DutchInstituteforFundamentalEnergyResearch,4ILTPE,NationalAcademyofSciencesofUkraine

Thereactivityofcommercialmetalcatalystsisoftensignificantlyinfluencedbythepresenceofdefects,suchassteps,kinks,oradatomsonthecatalyticsurface.[1,2]Correspondingly,thesticking of CO2, a crucial step e.g. in methanol synthesis, is expected to be structuredependent.InthisprocessCO2isgenerallypredictedtobetrappedandreactasamolecularlybound species.[3] On bare metal surfaces, the adsorption of CO2 is considered to bedependentontheworkfunction,whichdecreaseswiththeintroductionofdefects.[4]Ourcurvedcrystalapproachallowsustomodeltheinfluenceofsuchdefectsinacontrolledandsystematicmanner.[5]InthisstudyweemployacurvedPtcrystalswith(111)attheapexandgraduallyincreasingstepdensities,rangingfrom<1/μmto>1/nm.ThetwosidesofthecrystalfeatureA-andB-typestepsrespectively.WeexaminethestickingofCO2bymassspectrometryandscanningtunnelingmicroscopy.LowdosesofCO2atvaryingtemperaturesgiveusauniqueinsightintotheadsorptionandstructuralorganizationofCO2atwideterracesaswellashighlysteppedsurfaces.[1]K.Honkala,A.Hellman,I.Remediakis,etal.,Science2005,307,555.[2]L.Vattuone,L.Savio,M.Rocca,Surf.Sci.Rep.2008,63,101.[3]M.Behrensetal.,Science2012,336,893.[4]U.Burghaus,Prog.Surf.Sci.2014,89,161.[5]A.J.Walshetal.,J.Vac.Sci.&Technol.A2017,35,03E102;[5]J.Janlamooletal,Molecules2014,19,10845;[5]C.Hahnetal.,J.Chem.Phys.2012,136,114201.

November8,2017

24


Poster5

MimickinganAtomically-thin'VacuumSpacer'toMeasuretheHamaker

ConstantbetweenGrapheneOxideandSilica

LianyongChuetal.,TUDelft

Innanoscience,controloftheseparationbetweensurfaces,withsub-nmaccuracy,isoftenimportant.Forinstance,whenstudyingVanderWaals(VdW)forces1orcreatingnanogapsformoleculedetectionand separation2-4.Atnanometre-scale, 1Dor3D spacers, suchasnanotubesandnano-particles,aresusceptibletodeformation5.A2Dspacerisexpectedtoyieldamoreaccuratelydefinedseparation,owingtothehighatomdensityandstrengthinplanardirection.Herein,atomically thin2Dgrapheneoxide (GO)wasusedasnanometre-scale spacerwith sub-nmaccuracy, to study theVdW interaction.However, using such aphysicalspacerintroducesadditionalinteractions,obscuringtheinteractionsofinterest.Wedemonstratehowthesecontributionscanbeeliminatedbyeffectivelymimicingtheuseofa‘vacuumspacer’. In thisway,weobtain theeffectiveHamaker constantbetweenGOandsilica.1.Geim,A.K.;Grigorieva,I.V.,VanderWaalsheterostructures.Nature2013,499,419-425.2.Ward,D.R.;Grady,N.K.;Levin,C.S.;Halas,N. J.;Wu,Y.;Nordlander,P.;Natelson,D.,Electromigrated nanoscale gaps for surface-enhanced Raman spectroscopy. Nano letters2007,7,1396-1400.3.Lim,D.-K.;Jeon,K.-S.;Kim,H.M.;Nam,J.-M.;Suh,Y.D.,Nanogap-engineerableRaman-activenanodumbbellsforsingle-moleculedetection.Naturematerials2010,9,60-67.4.Li,H.;Song,Z.;Zhang,X.;Huang,Y.;Li,S.;Mao,Y.;Ploehn,H.J.;Bao,Y.;Yu,M.,Ultrathin,molecular-sieving graphene oxide membranes for selective hydrogen separation. Science2013,342,95-98.5. Sun, J.; He, L.; Lo, Y.-C.; Xu, T.; Bi, H.; Sun, L.; Zhang, Z.; Mao, S. X.; Li, J., Liquid-likepseudoelasticityofsub-10-nmcrystallinesilverparticles.Naturematerials2014,13,1007-1012.

November8,2017

25


Poster6ExperimentalrealizationandcharacterizationofanelectronicLieblattice

ThomasS.Gardenier1,MarlouR.Slot1,PeterH.Jacobse1,GuidoC.P.vanMiert2,SanderN.Kempkes2,StephanJ.M.Zevenhuizen1,CristianeMoraisSmith2,DanielVanmaekelbergh1

andIngmarSwart11DebyeInstituteforNanomaterialsScience,Utrecht,theNetherlands

2InstituteforTheoreticalPhysics,Utrecht,theNetherlandsE-mail:[email protected]

Novel two-dimensional materials with promising electronic band structures can beengineered by tailoring their lattice geometries. The honeycomb lattice of graphene, forinstance, gives rise toDirac cones inwhich charge carriersbehaveaseffectivelymasslessparticles.Thesquare-depletedgeometryofaLieblatticealsogivesrisetolinearlydispersingbands,similartographene,withaflatbandintersectingtheDiraccones.WhereasopticalandphotonicLieblatticeshavebeenstudiedexperimentally[1,2],anelectronicLieblatticehadnotbeenrealizedsofar.WereportontherealizationofanelectronicLieblatticeusingastrategysimilartothemethodemployed for creating artificial graphene [3]: carbonmonoxidemolecules onCu(111) arepositionedintoananti-latticebylateralmanipulationusinganSTMtip,confiningthecoppersurfacestateelectronsintothedesiredlattice.ThecharacteristicelectronicstructureoftheLieb lattice,assimulatedusingamuffin-tinandtight-bindingapproach,wasconfirmedbyscanning tunneling spectroscopy and wave-function mapping. Moreover, second-orderelectronicpatternswereobservedathigherenergies[4].TheCu(111)/CO system formsa versatilemodel system,which allowsone to studynovellattice geometries and to tune parameters that cannot be accessed in real solid-statematerials. The scanning tunnelling microscope facilitates the realization as well as thestructuralandelectroniccharacterizationofthelattice,pavingthewayforthedesignoftrulynoveltwo-dimensionalmaterials.References[1]D.Guzmán-Silvaetal.,NewJ.Phys.16,063061(2014)[2]S.Taieetal.,ScienceAdv.1,1500854(2015)[3]K.K.Gomesetal.,Nature483,306–310(2012)[4]M.R.Slot,T.S.Gardenieretal.,NaturePhysics13(2017)

November8,2017

26


Poster7

ForensicApplicationofAtomicForceMicroscopyforAge

DeterminationofBloodstains

ThreesSmijs(NFI),AmuHosseinzoi(NFI)andFedericaGalli(LU)

Forensic determination of the age of a bloodstain with little temporal error can provideimportantinformationinjudicialinquiry.Atomicforcemicroscopycouldprovideestimationsforbloodstainagesbasedontemporalchangesintheelasticityofredbloodcells(RBCs).Thistechnology enables RBC nano-indentations with the tip of a cantilever resulting in forcemeasurements and high resolution mapping of nanomechanical cell properties like theYoung’smodulusofelasticity.ThisstudyappliedatomicforcemicroscopytoinvestigatetheelasticityofrandomlyselectedRBCs from the peripheral zone of 4- to 8-day-old bloodstains (controlled laboratoryconditions). Special attention was paid to the condition of the silicon probes whencontinuously used to indent RBCs. The elasticity of 6 RBCs from a 5-day-old bloodstainappearedhomogeneousoverthecellwithameanYoung’smodulusof1.6±0.4GPa.Dataspreadingwasforonly6.5%causedbythechoiceoftheRBC.Uponageingofabloodstain,4to8days,asignificantageeffectwasobservedinRBCelasticity(4days:0.8±0.1GPa;5days:1.7±0.9GPa;6days:2.3±0.6Gpa;7days:4.5±0.6GPa;8days:6.0±1.8GPa;probespringconstants25.16-67.48N/m).Thespreadingbetweenthedata(4bloodstains;3RBCs/stain)enabledabloodstainagedeterminationwitha24hprecisiononlyfor6-to7-day-oldstains.Inothercasesa48htemporalaccuracywasobtained.Theconditionofthesilicontipwasregularlycheckedusingscanningelectronmicroscopyandan increasingbluntnessnoticedafter4to6cellindentations.Acorrectionfactorfortheincreaseintipradiuswasthereforeappliedfordataprocessing.Particularlyforcrimesceneinvestigationsamorerobusttipisrequiredtherebyincreasingbothprecisionandaccuracyoftheelasticitydata.

November8,2017

27


Poster8

NaClclustersgrownontopologicalinsulatorBi2Te3investigatedbyscanning

probemicroscopy

Asteriona-MariaNetsoua*,UmamaheshThupakulaa,AlexanderVolodina,AleksandrSeliverstova,TaishiChenb,FengqiSongc,andChrisVanHaesendoncka

a)Solid-StatePhysicsandMagnetismSection,KULeuven,BE-3001Leuven,Belgiumb)MaxPlanckInstituteforChemicalPhysicsofSolids,D-01187Dresden,Germany

c)NationalLaboratoryofSolidStateMicrostructures,CollaborativeInnovationCenterofAdvancedMicrostructures,andDepartmentofPhysics,NanjingUniversity,Nanjing210093,

China*[email protected]

Surfacepropertiesandtheirmodificationsoftopologicalinsulators(TIs)holdgreatpromisefordevelopinghigh-performanceelectronicsandapplicationsinquantumcomputing.Here,we choose to deposit nanometer sized atomic clusters of sodium chloride (NaCl) on thebismuth telluride (Bi2Te3) TI. The growth and electronic properties of different size NaClclusters on the Bi2Te3 were probed by means of scanning tunneling microscopy andspectroscopyunder lowtemperatureandultra-highvacuumconditions.WeobservedthatthedepositionofNaClonBi2Te3surfacesatroomtemperatureresults intheformationofNaClclusters,wheretheclustersizecanbecontrolledviathedepositiontime.Ourfindingsshow that the NaCl clusters alter the electronic properties of the TI surface of Bi2Te3 byinducingn-typedoping.CombiningtheactiveandpromisingareasofTImaterialsandclusters,ourstudymayofferanewmethodforlocaltuningofthetopologicalpropertiesandmaypavethewaytothefabricationofnanostructuredTImaterials.

November8,2017

28


Poster9

Tuningtheelectronicandmechanicalpropertiesofgraphenebyalcoholintercalation

E.Dollekamp,P.Bampoulis,M.H.Siekman,H.J.W.Zandvliet,E.S.KooijTUTwente

Inthiswork,weuseconductiveAFMandlateralforcemicroscopytostudytheelectronicandmechanicalpropertiesofgrapheneonamicasubstrate.Byloweringtherelativehumidityandconsecutivelypurgingwithalcohol,wecreatethreedistinctintercalantregions:anunaffecteddoublewaterlayer,2Dicefractalsandalcoholintercalatedonthe2Dicefractals.Thethreeregions show a clear difference in conductivity and friction. The graphene on the 2D icefractalsshowsahighconductivityandfriction;thegrapheneonthedoublewaterlayershowsamediumconductivityandfriction;andthegrapheneonthealcoholshowsalowconductivityandfriction.Thechangeinconductivityiscausedbydopingduetoapolarized2Dicelayer,which was validated with STM experiments by Bampoulis et al.[1] So, by changing theintercalantweareabletotunetheelectronicandmechanicalpropertiesofgraphene.[1]Bampoulis,P.; Siekman,M.H.;Kooij, E. S.; Lohse,D.; Zandvliet,H. J.W.;Poelsema,B.LatentHeatInducedRotationLimitedAggregationin2DIceNanocrystals.J.Chem.Phys.2015,143,034702.

November8,2017

29


Poster10

Pyridyl-functionalizedtriarylaminesself-assembledonAu(111)

LeonidSolianyk1,JuanCarlosMoreno-López1,JunLi1,StefanoGottardi1,MihaelaEnache1,UteMeinhardt2,MilanKivala2,MeikeStöhr1

1ZernikeInstituteforAdvancedMaterials,UniversityofGroningen,TheNetherlands2DepartmentofChemistryandPharmacy,UniversityofErlangen-Nürnberg,Germany

e-mail:[email protected]

Theengineeringofmolecularnanostructuresonwell-definedinorganicsurfacesisconsideredtobeessential forthedevelopmentof futurenanoelectronicdevices. Inordertobuildupnanostructureswith atomic precision, ultimate control over theunderlying interactions isneeded.In our work, we investigated the self-assembly of pyridyl-functionalized triarylamines onAu(111)byscanningtunnelingmicroscopy(STM),X-rayphotoelectronspectroscopy(XPS)andlowenergyelectrondiffraction(LEED).ForthedepositionofsubmonolayercoverageontoAu(111)heldatroomtemperature,aclose-packedphasewasobservedtoco-existwithtwostructurallydifferenthexagonalnanoporousnetworks.Theclose-packedphaseisstabilizedby hydrogen bonding while the nanoporous networks are held together by metal-ligandinteractionswithnative gold atoms. Thermal annealing at 180°C resulted in theexclusiveformationoftheAu-coordinatedhexagonalnanoporousnetworkwiththelargerporesize.BasedontheSTMandLEEDdata,thestructuralmodelscouldbepreciselydeterminedandwiththehelpof theadditionalXPSdata, the intermolecularaswellasmolecule-substrateinteractionswereunraveled.

November8,2017

30


Poster11

Exploringthepotentialofgraphenenanoribbonsasmolecularelectronicjunctions

MarkJ.J.Mangnus,PeterH.Jacobse&IngmarSwart

UtrechtUniversity

Recent developments in the field of on-surface chemistry have facilitated bottom-upfabricationofdefect-freegraphenenanoribbons(GNRs).1Stateoftheartscanningtunnellingmicroscopy(STM)techniqueshavehighlightedthepossibilityofformingamolecularjunctionbetweenametallicsubstrateandtheSTMtip2,3.Tocounteractthestrongelectroniccouplingto themetal surface,wedevelopedanovel techniquewherewe introduced intercalatinglayersofNaCl,allowingustomeasuretheelectronicconductancethroughsingleribbonsasafunctionofbiasvoltageandjunctionlength.4ThisworkisabigsteptowardstheapplicationofGNRsinmolecularelectronics.1.Cai,J.etal.Atomicallyprecisebottom-upfabricationofgraphenenanoribbons.Nature466,470–473(2010).2. Koch,M., Ample, F., Joachim, C.&Grill, L. Voltage-dependent conductance of a singlegraphenenanoribbon.Nat.Nanotechnol.7,713–717(2012).3.Jacobse,P.H.etal.Electroniccomponentsembeddedinasinglegraphenenanoribbon.Nat.Commun.8,119(2017).4.Wang,S.etal.Giantedgestatesplittingatatomicallyprecisegraphenezigzagedges.Nat.Commun.7,11507(2016).

November8,2017

31


Poster12

UniversalityofpseudogapandemergentorderinlightlydopedMottinsulators

KoenMBastiaans(1),IreneBattisti(1),VitalyFedoseev(1),AlbertodelaTorre(2,3),NikosIliopoulos(1),AnnaTamai(2),EmilyCHunter(4),RobinSPerry(5),JanZaanen(1),Felix

Baumberger(2,6),MilanPAllan(1)(1)LeidenUniversity,(2)UniversityofGeneva,(3)CaliforniaInstituteofTechnology,(4)

UniversityofEdinburgh,(5)UniversityCollegeLondon,(6)PaulScherrerInstituteHigh temperature superconductivity as it manifests in the cuprates was for long timesuspectedtobestronglyrelatedtothecopperoxidelayers,andthereforespecifictoonlythisfamilyofmaterials.Here,weinvestigatetheiridate(Sr1-xLax)2IrO4,belongingtoanewclassofquasi-2DeffectiveMottinsulators[1],whichwehaveshowntoexhibitphenomenastrikinglysimilartothecuprates[2-4].Weusespectroscopic-imagingscanningtunnelingmicroscopytovisualize the electronic structure at different doping concentrations. We measure fullygappedspectraatlowdopingconcentrations(x<4%)evenatthepreciselocationofdopantatomsthatarevisibleinthetopograph.ThisisevidenceforanimpuritybandMotttransitionoftheextracarriers,andthattheyaremoredeeplytrappedthaninthecuprates.Onlyatacertain doping threshold, the gap collapses revealing a pseudo gap and complex chargearrangements.[1]Kim,B.J.,etal.PRL101.7(2008):076402.[2]Kim,Y.K.,etal.NaturePhysics12.1(2016):37-41.[3]DeLaTorre,A.,etal.PRL115.17(2015):176402.[4]Battisti,I.,Bastiaans,K.M.,etal.NaturePhysics13.1(2017):21-25

November8,2017

32


Poster13

Sensingthenon-collinearmagneticstructurebycombiningmagneticexchangeandspin-polarizedimaging

N.Hauptmann1,T.Hung1,J.Gerritsen1,M.Dupé2,D.Wegner1,B.Dupé2,A.A.Khajetoorians1

1RadboudUniversity,InstituteforMoleculesandMaterials(IMM),6500GLNijmegen,The

Netherlands.2InstituteofPhysics,JohannesGutenbergUniversität,55128Mainz,Germany

Non-collinear magnetic structures, as skyrmions and spin spiral for instance, have beenpredictedbeingacandidateformagnetic-basedstorageandspintronicapplications.OnekeymechanisminthesemagneticstructuresistheDzyaloshinskii-Moriyainteraction(DMI),whichemerges in the absenceof inversion symmetry and the appearanceof strong spin-orbitalcoupling.Thenon-collinearmagneticstructurealsostronglydependsonthesymmetryofthegeometric structure.For investigating non-collinear magnetic structures, spin-polarizedscanningtunnelingmicroscopy(SP-STM)haslongbeenusedtocharacterizethemagnetismofsurfaceswithatomicspatialresolution.However,theSP-STMimagesrevealnotonlythemagnetic informationbut convolutedwithelectronicand structuralproperties.ByutilizingSPEX,a new combination of spin-polarized scanning tunneling microscopy (SP-STM) andmagneticexchangeforcemicroscopy(MExFM),weobtainmoredetailedinformationonbothnanoscale skyrmions and a spin spiral system on mono-and bilayers of iron on aniridiumsurface.Weshowthatwecanresolvetheskyrmionlatticeinthemonolayerandrevealtheinfluenceofthesurfacereconstructiononthemagnetisminthebilayer.

November8,2017

33


Poster14

AssembledferromagneticclusterchainsonanultrathinaluminiumoxidelayeronNi3Al(001)

KongyiLi,OlegKurnosikov,andBertKoopmansDepartmentofAppliedPhysics,EindhovenUniversityofTechnology,theNetherlands

Self-assembledchainsofFeclustershavebeengrownonanultrathinaluminiumoxidelayeron Ni3Al(001) by using atomic beam deposition. The non-wetting property of Fe on anoxidized surface leads to a formationofwell-defined clusters arranged in the chains. Thediameter of composed clusters can be controlled by the Fe coverage and the substratetemperature.Combiningwiththein-situtipmanipulationinascanningtunnellingmicroscope(STM),Feclustersonandoffthechainscanberemovedonebyoneorplacedintheexistingchain.Bythisway,anisolatedclusterchainisfabricated.TheSTM-tipmanipulationdoesnotonlyprovideatooltochangethegeometricalarrangementoftheclusterchainbutcanalsobeusedtomodifytheclustersinthechain.Fabricatedchainsofferromagneticclusterswoulddemonstratetheeffectsconnectingtheirferromagneticarrangementwithcurrenttransportinthefollowingin-situfour-probe-STMmeasurement.

November8,2017

34


Poster15

Au(111)isnotasuitablesubstratetostudymodelCoMoShydrodesulfurizationcatalysts

M.K.Prabhu,A.vanVark,C.Koskamp,B.Hagedoorn,I.M.N.Groot*LeidenInstituteofChemistry

UsingScanningTunnelingMicroscopyandX-rayPhotoelectronSpectroscopy,weinvestigatedthedirect sulfidation and theoxide route to synthesizeAu(111)-supportedCoMoSmodelhydrodesulfurization (HDS) catalysts. The results demonstrate strong cobalt-substrateinteractionsinthepresenceofhydrogensulfide.DirectsulfidationrouteproducessheetsofcobaltsulfidewithvariousstoichiometrythatnotonlycorrodetheterracesofAu(111),butalsodisplacetheMoS2crystallites,especiallyathighcobalt loadings.Theresultingsurfaceroughnessandclusteringoftheactivephaseleadstopossibleblockingofactivesites.Theoxiderouteontheotherhand,showsdifferentialsulfidationofthemolybdenumandcobaltoxides.Thecobaltsulfidephaseencapsulatesthestillsulfidingmolybdenumoxideparticlesandformsa2Dcore-shell-likesystemwhichpreventsthecompletesulfidationofMoS2.ThelatticemismatchwithAu(111)favorsthereductionoftheoxideprecursorspre-sulfidation.Additionally, the strain induced by the 2D shell formation promotes the growth ofmolybdenumsulfideoverthecobaltsulfidesheetsuponextendedsulfidation.TheseeffectshavenotbeenobservedinaluminaindustrialHDScatalystsreportedsofar.WerecommendthatbyusinganoxidesubstratesuchasrutileTiO2(110),itmaybepossibletoobtainamodelsystemthatbetterrepresentstheindustrialHDScatalysts.

November8,2017

35


Poster16

DefectDominatedChargeTransportandFermiLevelPinninginMoS2/MetalContacts

KaiSotthewes,PantelisBampoulis,RikvanBremen,QirongYao,BenePoelsemaandHarold

J.W.ZandvlietPhysicsofInterfacesandNanomaterials,MESA+InstituteforNanotechnology,Universityof

Twente,P.O.Box217,7500AEEnschede,TheNetherlands

Understanding the electronic contact between molybdenum disulfide (MoS2) and metalelectrodesisvitalfortherealizationoffutureMoS2-basedelectronicdevices.NaturalMoS2has the drawback of a high density of bothmetal and sulfur defects and impurities.Wepresent evidence that subsurfacemetal-like defectswith a density of∼1011 cm−2 inducenegative ionization of the outermost S atom complex. We investigate with high-spatial-resolution surface characterization techniques the effect of these defects on the localconductance of MoS2. Using metal nanocontacts (contact area < 6 nm2), we find thatsubsurface metal-like defects (and not S-vacancies) drastically decrease the metal/MoS2Schottkybarrierheightascomparedtothat in thepristineregions.Themagnitudeof thisdecrease depends on the contact metal. The decrease of the Schottky barrier height isattributedtostrongFermilevelpinningatthedefects.Indeed,thisisdemonstratedinthemeasured pinning factor, which is equal to ∼0.1 at defect locations and ∼0.3 at pristineregions.Ourfindingsareingoodagreementwiththetheoreticallypredictedvalues.Thesedefectsprovidelow-resistanceconductionpathsinMoS2-basednanodevicesandwillplayaprominentroleasthedevicejunctioncontactareadecreasesinsize.

November8,2017

36


Poster17

Scanningprobemicroscopyatmagneticfieldsupto34T

L.Rossi1,J.Gerritsen2,L.Nelemans1,A.Khajetoorians2,B.Bryant1

1HighFieldMagnetLaboratory,RadboudUniversity,Nijmegen,theNetherlands2SPMgroup,InstituteforMoleculesandMaterials,RadboudUniversity,Nijmegen,the

Netherlands

Up to now, low temperature Scanning Probe Microscopy (SPM) has been limited to amagneticfieldstrengthof18T,asthemajorityofdesignshavebeenbasedonsuperconductormagnets.Forsomeexperimentalapplications–forexamplethestudyoffractalspectra ingraphenesuperlattices,theroomtemperaturequantumHalleffectandsomemetamagnetictransitions–higherfieldsarerequired.Staticfieldsofmorethan30Tcanbegeneratedindedicatedhigh-field facilitiesbywater-cooled, resistiveBittermagnetsorhybrid resistive-superconducting magnets. However, implementing SPM in a Bitter magnet is a majorchallenge,duetothehighlevelofvibrationalnoiseproducedbytheturbulentcoolingwater,inadditiontothestrongspaceconstraintsresultingfromthesmallmagnetbore.Wepresentanovel cryogenicScanningTunnellingMicroscope (STM)designed tooperateinside a water-cooled Bitter magnet, which can reach a magnetic field of 38 T. TheperformanceoftheSTMisdemonstratedthroughLandau leveltunnellingspectroscopyofgraphite,at4.2Kinmagneticfieldsupto34T.Additionallywe show thedesignof ahighly compactAtomic ForceMicroscope (AFM) foroperation at cryogenic temperatures in an extremely high magnetic field. We presentpreliminaryimagingdataonthefrustratedspinelCdCr2O4atupto30T.

November8,2017

37


Poster18

LowEnergyElectronMicroscopyatNearAmbientPressures

AndreasThissen;SPECSSurfaceNanoAnalysisGmbH,Germany

Low-energyelectronmicroscopy(LEEM)isaspectromicroscopytechnique,whichallowsthestudy of dynamic processes at surfaces and interfaces, such as thin-film growth, surfacereactions,andphasetransitions.WiththeFELEEMP90fromSPECS,which isbasedontheinstrumentdesignbyRudolfTrompfromIBM[1,2],lateralandenergyresolutionofbelow5nmand250meV,respectively,canbeachieved.Dependingontheexcitationsourceandthesettingsontheinstrumentavarietyofdifferentimagingmodesarepossible:mirrorelectron microscopy, low energy electron diffraction (LEED), phase contrast imaging,reflectivity contrast, dark field imaging and bright field imaging, aswell as photoelectronemissionmicroscopyandspectroscopy.WehaveenhancedthetechnicalcapabilitiesoftheFE-LEEMP90towardsstudiesundernearambientconditionsbydevelopinga special samplegeometry.Thisenables theanalysisofmaterialsanddevicesundernearambientconditionsandeveninsituduringoperation.

November8,2017

38


Poster19

Localatomicstructureandelectronicpropertiesof

graphene/Cu(111)/Al2O3substrateviascanningtunnelingmicroscopyandspectroscopy

UmamaheshThupakula†,*,Asteriona-MariaNetsou†,AleksandrSeliverstov†,Bart

Vermeulen‡,StevenBrems‡,andChrisVanHaesendonck†

†Solid-StatePhysicsandMagnetismSection,KULeuven,BE-3001Leuven,Belgium‡Imecvzw,Kapeldreef75,B-3001Leuven,FlemishBrabant,Belgium

*[email protected]

Grapheneisasinglelayerofcarbonatomsarrangedinahexagonalhoneycombpattern.Thistwo-dimensionalhoneycombstructureofcarbonhasdrawnmuchattentioninthepastonedecadeduetoitsapplicabilitytothemostpromisingnanoelectronicsapplication.1Indeed,atomicscaleinvestigationsoftheelectronicpropertiesofgrapheneareplayingacrucialrolein understanding and tuning the exotic properties of thismaterial for its potential deviceapplications.2Inthisregard,scanningtunnelingmicroscopy(STM)andspectroscopy(STS)areunique techniques for atomic scale investigations and have been extensively used ingraphene research. Inourwork,weexplore the local atomic andelectronicpropertiesofgraphenegrownonCu(111)on sapphire substrate.We facilitate to study theatomic andelectronicstructurebehaviorofdefectfreeregionsofgraphene,grainboundaries,effectofintrinsicatomicdefects ingraphene(carbonvacancy)andpointdefects incopper.Locally,irregular moiré pattern under negative bias in the absence of grain boundary has beennoticed.PositiondependentSTSattheatomicscalehasbeenusedtocorrelatetheatomicstructureandelectronicpropertyofgrapheneonCu(111)/Al2O3.

1)A.ZurutuzaandC.Marinelli,Nat.Nanotechnol.9,730-734(2014)2)M.M.Ugeda,I.Brihuega,F.GuineaandJ.M.G.Rodriguez,Phys.Rev.Lett.104,096804(2010)

November8,2017

39


Poster20

MagneticResonanceForceMicroscopy:ProbingSmallSpinEnsemblesin3D

GesaWelker,MartindeWit,MarcdeVoogd,JelmerWagenaar,LuciaBossoni,TjerkOosterkamp

LeidenUniversity

Magnetic Resonance ForceMicroscopy (MRFM) is a scanning probe technique for locallyprobingspin-relatedmaterialpropertieswitharesolutionof10-100nm.Theuseofmagneticresonanceallowsfordetectingspinsnotonlyonthesamplesurface,butalsointhebulk.We developed anMRFMwith a base temperature of 10mK. As a proof of principle, wedemonstrated measuring the nuclear spin-lattice relaxation time of copper at sampletemperaturesdownto42mK.Asexpected,wefindKorringa-behavior.Furthermoreweusedoursetuptodeterminetheimpurityspindensityindiamond.These are important steps on the way to investigating more complicated samples withinhomogeneous electron properties, such as iron-doped palladium, oxide interfaces,topologicalinsulatorsorstronglycorrelatedelectronsystems.

November8,2017

40


Poster21

COoxidationonPt7onh-BN/Rh(111):Stabilityandcatalyticactivity

HamedACHOURetal.,EPFL,Switzerland

Thecomplexityofrealcatalystsintermsoftheirelectronicandgeometricstructureandtheirinteractionwiththesupportmakesfundamentalstudiesmuchsimpleronmodelcatalysts.InthiscontributionwereportonthestabilityandCOoxidationonmassselectedPt7supportedonhexagonalboronnitride(h-BN)grownonaRh(111)surface.Inthefirstcase,theideaofourexperimentsistoreducethesizeofcatalyticparticlestotheirultimatelimitinordertomakecarexhaustcatalyststhatcontain lessPt. Inthesecondcase,the inerth-BNlayer isexpectedtominimizetheeffectofthesupportonthecatalyticreactionandwillalsobeusedasanorderedarraytostabilizethesmallPtparticles.h-BNformsasinglesp2bondedatomichoneycomb layer. The misfit with the underlying Rh(111) surface leads to a stronglycorrugatedMoirépatternwith2nmdiameterareasthatarestronglyboundandsurroundedby1nmwideareasthatareonlyvan-der-Waalsboundand1Åhigher.Thelow-lyingregionsof theMoiré are known to be good trapping centers formolecules and clusters. Recentstudiesshowthath-BNpresentsagreatpotentialasfuturecatalystssupport[1].Thestabilityof thePtnanoparticles is investigated in-situbymeansofScanningTunnelingMicroscopy(STM),operatedat80K.CatalyticreactionsonthecatalystaremeasuredinsituinacustommadeUHVreactor.COoxidationhasbeenstudiedusingalternating13C16Oand18O2pulses,(atafrequencyof0.2Hz)onthePt/h-BN/Rh(111)catalystasafunctionoftemperature(300-700K).We find thatPt clustersannealed to700Kexhibit Smoluchowski ripening,above,intercalationofthePtunderh-BNtakesplace.Thestabilityisstronglyreducedunderreactionconditions,aphenomenonwhichhasalsobeenobservedforothersystemssuchasCo/h-BN/Rh(111)[2]andPt/TiO2(110)[3].TheonsettemperatureoftheCOoxidationisat500Kandtherebyhigherthanontitania[4]. Intercalatedclustersexhibitaby100K loweronsettemperatureoftheCOoxidationreactionthusimprovingthecoldstartbehavior.[1]X.Duo.etal.TheoreticalStudyoftheDepositionofPtClustersonDefectiveHexagonalBoronNitride(h-BN)Sheets:Morphologies,ElectronicStructures,andInteractionswithO.J.Phys.Chem.C.118,8868-8876(2014).[2]B.Preobrajenski.etal.ImpactofOxygenCoadsorptiononIntercalationofCobaltundertheh-BNNanomesh.NanoLett.9,2780-2787(2009).[3]S.Bonanni.etal.Reaction-InducedClusterRipeningandInitialSize-DependentReactionRatesforCOOxidationonPtn/TiO2(110)-(1Å~1).J.Am.Chem.Soc.136,8702-8707(2014).[4]S.Bonanni.etal.OvercomingtheStrongMetal−SupportInteractionState:COOxidationonTiO2(110)-SupportedPtNanoclusters.ACSCatal.1,385-389(2011).

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Exhibitors/Sponsors

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List of participants

Lastname Infix Firstname Affiliation

Achour Hamed LeidenUniversity

Ackermans Philip UniversityLeiden

Alarcon Esther Amolf

Alekseeva Yulia SPECSSurfaceandNanoanalysisGmbH

Allan Milan LeidenUniversity

Ashworth Timothy ZurichInstrumentsAG

Auras Sabine LeidenUniversity

Baarle van Gertjan LPM

Bakker Johan LeidenUniversity

Bampoulis Pantelis UniversityofTwente

Barsukoff Daan UniversityLeiden

Bastiaans Koen LeidenUniversity

Battisti Irene LeidenUniversity

Beernink Pieter PIBenelux(PhysikeInstrumente)

Benschop Tjerk LeidenUniversity

Berghaus Thomas nanoscoregmbh

Boden Dajo LeidenUniversity

Bollmann Tjeerd UniversityofTwente

Bremen van Rik UniversityofTwente

Bryant Benjamin HighFieldMagnetLaboratory

Burshille PeerA. NanoAndMoreGmbH

Bus Marcel DelftUniversityofTechnology

Castenmiller Carolien UniversityofTwente

Cho Doohee LeidenUniversity

Chu Liangyong TUDelft

CIFTCI TUUNSJ TU/e

CoffeyBlanco David TUDelft

Deng Xin LeidenUniversity

Dollekamp Edwin UniversityofTwente

Duval Jessica Scientec

Elbertse Robbie TUDelft

Emmanuel Lepleux CSInstruments

Ettema Ad ScientaOmicron

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Freeney Saoirse UtrechtUniversity

Galli Fedrica LION

Gardenier Thomas UtrechtUniversity

Gautier-Bergman Mirthe LeidenUniversity

Geluk Arjen UniversiteitLeiden

Gobeil Jeremie TUDelft

Gonzalez-Garcia Yaiza DelftUniversityofTechnology

Groot Irene LeidenInstituteofChemistry

Heerlein Holger NanoAndMoreGmbH

Heidema Pieter Hositrad

Heyde Markus FritzHaberInstitute

Hung Tzu-Chao RadboudUniversity

Jacobse Peter UtrechtUniversity

Jacobse Leon LeidenUniversity

Johann Florian OxfordInstruments,AsylumResearch

Juurlink Ludo LeidenUniversity

Kalff Floris TUDelft

Kap Özlem UniversityofTwente

Katan Allard DelftUniversityofTechnology

Koppers Remco PfeifferVacuumBenelux

Krammel Christian EindhovenUniversityofTechnology

Kurnosikov Oleg EindhovenUniversityofTechnology

Kwiecinski Wojciech UniversityofTwente

Leeuwenhoek Maarten LeidenUniversity&DelftUniversity

Lesko Samuel BrukerNanoSurfacesDivision

Li Kongyi EindhovenUniversityofTechnology

Liu Tiancheng LeidenUniversity

Mangnus Mark UtrechtUniversity

Markus Patrick Bruker

MartínezVelarte MariadelCarmen TUDelft

Netsou Asteriona-Maria KULEUVEN

Opdam Daniël Leidenuniversity

Otte Sander DelftUniversityofTechnology

Prabhu MaheshKrishna UniversityLeiden

Prokop Jacek SchaeferTechnologieGmbHRodriguezdaCruz Adonai EindhovenUniversityofTechnology

Rose Volker ArgonneNationalLaboratory

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Rossi Lisa HFML,RadboudUniversity

Ruitenbeek van Jan LeidenUniversity

Schaefer Martin SchaeferTechnologieGmbH

Schenkel Fred UniversityofLeiden

Seliverstov Aleksandr KULeuven

Sfiligoj Cristina ARCNL

Siekman Martin UniversityofTwente

Sjardin Arthur LeidenProbeMicroscopy

Slot Marlou UtrechtUniversity

Smijs Threes NFI

Solianyk Leonid UniversityofGroningen

Sotthewes Kai UniversityofTwente

Swart Ingmar UtrechtUniversity

Thupakula Umamahesh KULeuven

Tiger Carl-Johan TechnicalUniversityEindhoven

Tran van Bay UniversityofGroningen

Tuijnvander P. LeidenProbeMicroscopyb.v.

VanHaesendonck Chris KULeuven

vanRuitenbeek Jan UniversiteitLeiden

Vermeeren Pascal UniversiteitUtrecht

Vollema Victor ARCNL

Volodin Alexander KatholiekeUniversiteitLeuven

Vries de Niels EindhovenUniversityofTechnology

Weisser Ludger ParkSystemsEuropeGmbH

Welker Gesa LeidenUniversity

Wenzel Sabine UniversityLeiden

Winkel Alex JPKInstrumentsLtd

Wit de Martin LeidenUniversity,LION

Yetik Gorsel ARCNL

YILMAZ AYTAC TUDELFT

Zoetemelk Raimon STInstruments

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Leiden Institute of Chemistry Leiden University

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