High-T Superconducting Electronic Devices Based on YBCO ...

298IEICE TRANS. ELECTRON., VOL.E96–C, NO.3 MARCH 2013

INVITED PAPER Special Section on SQUID & its Applications

High-Tc Superconducting Electronic Devices Based on YBCOStep-Edge Grain Boundary Junctions

Shane T. KEENAN†a), Jia DU†, Emma E. MITCHELL†, Simon K. H. LAM†, John C. MACFARLANE†,Chris J. LEWIS†, Keith E. LESLIE†, and Cathy P. FOLEY†, Nonmembers

SUMMARY We outline a number of high temperature superconduct-ing Josephson junction-based devices including superconducting quantuminterference devices (SQUIDs) developed for a wide range of applicationsincluding geophysical exploration, magnetic anomaly detection, terahertz(THz) imaging and microwave communications. All these devices arebased on our patented technology for fabricating YBCO step-edge junctionon MgO substrates. A key feature to the successful application of devicesbased on this technology is good stability, long term reliability, low noiseand inherent flexibility of locating junctions anywhere on a substrate.key words: Josephson junction, grain boundary step edge junction, hightemperature superconductor, SQUID, THz imaging, mineral exploration,magnetic anomaly detection, unexploded ordnance detection, microwavedevices

1. Introduction

Soon after the discovery of high-temperature-superconduc-tivity (HTS) in the mid 1980s, efforts were initiated to de-velop viable fabrication technologies for the preparation andstudy of reliable Josephson junctions made from thin filmsof HTS materials such as YBCO. By 1990, it was clear thatgrain boundary junctions (GBJs), either naturally-occurringor engineered, possessed many of the properties required forthe practical implementation of Josephson-effect junctionsand devices. A comprehensive survey of GBJ types and theirproperties was published at that time by Gross [1]. In Sect. 2of this paper, we concentrate on the step-edge formation andproperties, as described by many research groups [2]–[6],which is key to CSIRO’s successful development of step-edge GBJs in thin YBCO films on MgO [100] single-crystalsubstrates. The critical GBJ properties included: transitiontemperatures, Tc, junction critical current, Ic, normal resis-tance, Rn, characteristic voltage, IcRn, and low levels of in-trinsic critical current fluctuations or voltage noise, S v. In-cremental improvements in the technique over 25 years en-abled fundamental studies of magnetic flux pinning [7] andnoise mechanisms [8], and led to many successful deviceapplications. These range from geomagnetic prospecting,through microwave communications [9] THz imaging [10]and are described briefly in Sects. 3–5.

Manuscript received July 30, 2012.†The authors are with CSIRO Division of Materials Science

and Engineering, P.O. Box 218 Lindfield 2070, Sydney, Australia.a) E-mail: [email protected]

DOI: 10.1587/transele.E96.C.298

2. YBCO Step-Edge Josephson Junctions & SQUIDs

2.1 Step-Edge Junction Design and Fabrication

The HTS junctions, SQUIDs and other sensors described inthis review are all based on step-edge Josephson junctions(SEJ) fabricated by depositing a thin YBCO film (≈ 200 nm)onto an MgO substrate in which a step (≈ 400 nm deep) hasbeen ion-beam etched. Details of the method, which mayenable the junction’s position on the substrate to be predeter-mined anywhere on the substrate chip, can be found in ref-erences [11], [12]. CSIRO developed a patented method formaking step-edge GBJs in the late 1990’s [13] with severalfactors contributing to the success of these devices. Theseinclude the ability to ensure a single YBCO grain boundarygrows at the top edge of the MgO step only, whilst main-taining a rounded lower step profile with no second junction(Fig. 1(top)). Another feature of this junction type is thatYBCO always grows with its c-axis normal to the MgO sur-face, including the sloping surface of the step [12]. Thisresults in a grain boundary junction formation where the su-perconducting thin films’ crystal structure is rotated aboutthe YBCO a-b-axis producing a misalignment of the c-axisas the film forms over the slope of the step. This type of rota-tion produces junctions that are closer in structure to [100]-tilt junctions (Fig. 1(bottom)) than the more commonly stud-ied [001]-tilt junctions produced using bicrystal substrates,in which the two superconducting electrodes are rotated in-plane about the c-axis [14]. The grain boundary orientationstrongly influences the transport properties [12], [15], andfor step-edge junctions, provides certain advantages suchas reduced critical current fluctuations in applied magneticfields [16].

The TEM cross-section in Fig. 1(bottom) demonstratesthat step-edge junctions have a clean, narrow (≈ 1 nm) grainboundary junction region (arrows) with atomic alignment ofYBCO planes meeting at an angle equal to the step-angle,typically around 36◦. Just as the in-plane misorientation an-gle, θ, strongly determines the junction critical current den-sity, Jc, of [001]-tilt junctions [15], the step-angle, φ, affectsthe step-edge junction Jc, but to a lesser degree [12].

These step-edge junctions display large IcRn products≈ 3–5 mV at 4.2 K which are approaching the best valuesachieved by other [100]-tilt junctions [17], and are gener-ally higher than [001]-tilt junctions. Constant IcRn vs Jc

Copyright c© 2013 The Institute of Electronics, Information and Communication Engineers

KEENAN et al.: HIGH-Tc SUPERCONDUCTING ELECTRONIC DEVICES BASED ON YBCO STEP-EDGE GRAIN BOUNDARY JUNCTIONS299

Fig. 1 TEM images of a YBCO step-edge junction cross-section in thea-c plane taken from [12]. (Top) The etched step profile in MgO (darkregion) reveals a sharp upper step-edge and rounded lower profile. TheYBCO is deposited over the step and the grain boundary junction whichpropagates through the YBCO film is shown in higher magnification in theTEM image below. Reproduced with permission from IOP, from Ref. [12],Fig. 3.

values in [100]-tilt junctions were attributed to direct tun-neling for both Cooper pairs and quasiparticles [17]. Thiscomparison highlights that step-edge junctions have differ-ent transport properties compared with [001]-tilt junctions.In addition, step-edge junctions are relatively inexpensiveto prepare, and show long-term stability [18], [19] and goodnoise performance as indicated by low critical current fluc-tuations [16], [19]. Recently, a few step-edge junctions thathad not been passivated but stored in a nitrogen gas cham-ber for over 10 years were re-measured. The Ic values hadreduced by 25–40%, while Rn had no significant change.Some of our rf and dc SQUIDs used in commercial systemsfor several years are still fully operational. Effective passi-vation techniques have also been investigated [18], [19] forimproving long term stability of the SQUIDs. Factors affect-ing the quality of step-edge junctions fabricated accordingto our procedure include the growth of YBCO in-plane mis-orientated grains due to surface contamination or degrada-tion of the MgO substrates [20], [21], the film critical currentdensity and film morphology [22], the MgO surface rough-

Fig. 2 (a) Ic and Rn values of a 3 μm SEJ against the IBE time-used withpermission [18]; (b) sub-micron junctions prepared by focused ion beammilling with a Pt protective layer over the step edge area.

ness [23] and the step-angle φ [11], [12].The typical range of Rn values is 1–10Ω for 2–3 μm

wide junctions. Post-fabrication trimming of the GBJ hasbeen developed [18], [19], [24] by means of Ar-ion beametching (IBE) (see Fig. 2(a)). This technique allows someadjustment of the junction’s Ic and Rn parameters to en-able optimization of a particular device. The Rn value canbe increased by reducing the junction width and height byIBE trimming. A focused ion beam milling technique (seeFig. 2(b)) is currently being investigated to fabricate submi-cron wide junction. Preliminary results show a 0.4 μm widejunction which has Rn with a value of ≈ 35Ω.

2.2 SQUID Development

HTS SQUID magnetometers need optimized junction andfilm characteristics for stable performance when operatingoutside magnetic shields. Parameters such as Ic and Rn mustbe optimized to achieve high voltage modulation depths andlow flux noise. For example, we evaluated the performanceof our 8 mm × 8 mm pickup loop, directly-coupled SQUIDmagnetometers for unshielded use. In a recent experiment,we characterized over 20 HTS dc SQUIDs in the labora-tory. The SQUIDs were directly coupled to a large pickup coil on a 1 cm × 1 cm MgO substrate. All the deviceshad the same SQUID design with an inductance of 65 pH.At T = 77 K, the majority of these devices had a peak-to-


Fig. 3 (Top) voltage-flux modulation of SQUID; (bottom) field noisespectrum of a typical CSIRO 8 mm SQUID measured inside magneticshielding.

peak modulation voltage greater than 30 μV with the high-est value close to 50 μV (top Fig. 3). Figure 3 shows themodulation voltage and noise spectrum for one of our recent8mm dc SQUIDs measured in a magnetically shielded envi-ronment. The noise floor of SQUID was about 56 fT/

√Hz

down to ≈ 10 Hz.

2.3 Increasing Flux-Locked Loop Slew Rate

There are many applications that require SQUID systems tomeasure not only very small signals but also rapidly chang-ing ones. In some applications, the dynamic range can beover 120 dB and requires a system slew rate of 10 mT/s.

SQUID read-out electronics currently available fallinto two distinct categories: either flux quanta counting sys-tems such as those described by Ludwig [25] or flux lockedloop (FLL) systems such as those described by Drung [26].While flux quanta counting systems have excellent dynamicrange and maximum slew rate, they suffer from excess noisewhen used with high temperature SQUIDs. On the otherhand, FLL systems have a high dynamic range and very lownoise but tend to exhibit lower slew rates.

We have developed a high slew rate SQUID read-outsystem that significantly increases the slew rate of a FFLwithout incurring the excess noise of flux counting systems.The system is based on a time multiplexed quadrature mod-ulation and detection scheme that allows linearization of theSQUID’s periodic transfer function. The linearized SQUIDsignal is then used as part of a FLL which is able to track theSQUID error signal over multiple flux quanta while main-taining the loop’s lock. The system was constructed usinga hybrid digital/analogue signal processing scheme that al-

Fig. 4 A typical response from the high slew rate SQUID read-outsystem attached to a 3 mm SQUID.

lows both complex modulation/demodulation methods andvery high dynamic range feedback to the SQUID. Resultsobtained with a CSIRO 8 mm YBCO SQUID include a noisefloor of 8.63 μΦo/

√Hz and a slew rate of 8.63 MΦo/s which

is very much faster than previous electronics used. Figure 4shows a typical response from the new electronics attachedto a 3 mm SQUID.

3. Geomagnetic Exploration

The discovery and exploitation of mineral ore bodies hasrelied heavily on magnetic measurement techniques. Sub-terraneous, on-surface and airborne equipment, most com-monly utilizing Transient Electromagnetic (TEM) and Mag-netotelluric (MT) methods, can be applied in many situa-tions. Other applications in addition to mineral explorationinclude sub-sea mapping and archaeometric studies. Forthese applications, the sensitivity of superconducting de-tectors to low-frequency (0.01 Hz–10 kHz) magnetic fieldsand/or gradients is their most important property [27], [28].

Over the past 20 years, CSIRO has developed su-perconducting sensor systems for TEM prospecting [29].CSIRO has licensed a product, known as LANDTEM,which is widely used for the detection and delineation ofhighly conducting ore bodies such as nickel sulphides, sil-ver and gold [29]. Figure 5 shows a schematic of the wayTEM is undertaken in the field.

Initially this work was undertaken, with some earlysuccesses, in collaboration with BHP P/L, now BHP Bil-liton. Later in 2000, the SQUID sensor was successfullyused to delineate nickel sulfide targets at Falconbridge Ltd.’sRaglan, Quebec, mine site [29].

The ability of our SEJ based SQUIDs to operate un-shielded with low intrinsic noise makes these devices ideallysuited for these demanding geophysical applications. Thisprogress was greatly facilitated by ingenious patented [30]cryogenic innovations (Fig. 6) which made SQUID deploy-ment in remote field situations relatively stress-free [29].The critical breakthrough achieved with LANDTEM wasenabled transient magnetic fields to be recorded on much


Fig. 5 Schematic of TEM for geological survey.

Fig. 6 A LANDTEM portable liquid nitrogen cryostat and SQUIDelectronics package.

longer time-scales than was previously possible, an increasein “off times” from about 50 ms to seconds. The improvedsensitivity of HTS SQUIDs extends the signal to noise ratioof target signals making it possible to detect mineral bod-ies either while buried under conductive cover or at greaterdepths than was previously possible using inductive coilsensors. Figure 7 and Fig. 8 compare TEM decay profilesfor a HTS SQUID sensor and an induction coil receiverrecorded during surveys over two targets. These figuresshow the strength of the induced signal response as a func-tion of the time after the TEM pulse was switched off. Theoff-time signal is integrated over a number of time intervalswith the interval widths increasing quasi-logarithmaticallyfor later times. Numbers (channels) are assigned to theseintegration intervals. For the system used for these surveys;the channels were centred at times ranging from 0.043 ms(channel 1) to 766 ms (channel 48). The first target, Mag-gie Hays North, was a relatively shallow target with itsupper extent reaching approximately 100 m below the sur-face. This target was easily detected using both systems,see Fig. 7. A comparison of the two sensors responses atoff time “channel 18”, shows that the SQUID response issignificantly more pronounced than is the induction coil re-sponse. This is known as the “early time advantage” of Bfield sensors over dB/dt sensors [29].

The second target, Maggie Hays, was a much deepertarget with the upper extent of the ore body approximately400 m below the surface. The coil data could hardly detectthe response of the ore body while the SQUID data shows

Fig. 7 (Top) TEM response of the Maggie Hays North deposit recordedby an induction coil sensor and (bottom) by a HTS SQUID sensor. Channeltimes range from 0.043 ms (channel 1) to 766 ms (channel 48). Publishedwith the permission of Lion Ore, Australia.

it clearly, see Fig. 8. Note that, to try to achieve a clearlyobservable response in the induction coil sensor, the trans-mitter current was increased to a level greater than that usedwhen collecting the SQUID data.

4. Magnetic Anomaly Detection

4.1 Underwater UXO Detection

Large areas of the marine environment are contaminatedwith unexploded ordnance (UXO) remaining from militarytesting and training. In order to further develop this envi-ronment after military use, 99.9% detection of UXOs mustbe achieved. For this reason, CSIRO have developed a mag-netic tensor gradiometer based high-Tc SQUID technology,which improves the ability to detect, localize and charac-terize these small projectiles where conventional magneticsensor systems fail to deliver adequate performance. Thefull gradient tensor data provides detailed information abouta target, in a single pass, without necessarily passing di-rectly over the target. The gradient tensor components al-low you to determine the location of the target using a di-rect method, rather than the indirect inversion method re-quired with total-field or vector measuremnts. Additionally


Fig. 8 (Top) Profile of the main Maggie Hays deposit recorded by aninduction coil sensor and (bottom) by a SQUID sensor. A 200 m × 200 mloop was used for this survey. The transmitter coil current was 25 A forthe coil and 20 A for the SQUID sensors respectively. Published with thepermission of Lion Ore, Australia.

magnetic moment magnitude and target orientation are mea-sured directly aiding in the discrimination and characteriza-tion of ordnance and magnetic debris [43].

The full tensor is calculated using an array of six planarSQUID gradiometers positioned on the slant faces of a trun-cated hexagonal pyramid, shown schematically in Fig. 9(b)[31]. The individual sensors have gradient field sensitivi-ties in the range of ≈ 1–2 pTrms/m/

√Hz (at 10 Hz) as seen

in Fig. 9(a). This level of sensitivity allows us to detectordnance of with a minimum dipole moment of 0.01 Am2

(40 mm calibre) at a standoff of ≈ 4 m. The system alsoincorporates a number of reference SQUID magnetometersused to determine the local magnetic field vector compo-nents. These magnetometers are used to compensate forany residual gradiometer sensitivity to common mode sig-nals thus improving the system balance. This technique re-duces system sensitivity to small angular movements in theEarth’s magnetic field thereby making mobile applicationfeasible. For mobile real world magnetic surveying wherethe common mode signal is large, to ensure success of thistechnique, the system must be calibrated to an extremelyhigh level of precision.

Figure 9(c) shows an example of the five independent

Fig. 9 (a) Intrinsic gradient sensitivities of ≈ 1–2 pTrms/m/√

Hz at 10 Hzwere achieved for all devices (shielded), 4–5 pTrms/m/

√Hz (unshielded

lab) and reduced to the intrinsic shielded noise floor again in a remote lo-cation, (b) Schematic diagram of system showing the SQUID gradiometerson truncated hexagonal pyramid with SQUID reference sensors, (c) Theextracted five independent tensor components in response to a moving tar-get.

gradient tensor components extracted from the compen-sated individual gradiometer outputs measured in responseto a passing magnetic anomaly (magnetic dipole moment≈ 7 Am2) at a distance of 2 m from the system while sta-tionary.

4.2 Rotating Gradiometer

An alternative technique to using an array of planar gra-diometers for measuring the full magnetic gradient tensor


Fig. 10 (a) A rotating gradiometer consisting of a dc-SQUID magne-tometer inductively coupled to a flux transformer and a planar supercon-ducting shield, and (b) a patterned Au/YBCO flexible tape transformer[32], [33].

Fig. 11 Comparison of the measured detection limits of SQUID, coil,and X-ray system for SS316 needle pieces [34].

was also developed by CSIRO. Rotating an axial gradiome-ter about its central axis enables the gradient informationin a magnetic signal to be distinguished from the common-mode signal via frequency separation [32], [33]. As shownin Fig. 10, a DC SQUID magnetometer is inductively cou-pled to a patterned flexible superconducting flux transformerand to a superconducting shield to form a 1st order axial gra-diometer [32], [33].

4.3 Metal in Food Detector

CSIRO developed a prototype metal detector using DCSQUIDs to detect stainless steel fragments for quality assur-ance in manufacturing [34]. Figure 11 shows a comparisonof the detection limits between the SQUID, coil, and X-rayfor stainless steel particles in different packages. It showsthat, for the magnetized samples, the SQUID system is su-perior over the coil system in all cases and similar or betterthan the X-ray system.

5. Radiofrequency Applications

5.1 Telecommunications

HTS materials have some unique properties which are suit-able for a variety of high-frequency applications [9], [35].

Fig. 12 (Top) 2-junction resistive SQUID oscillator/mixer; (bottom) anexample of mixing spectrum with signal (right) local oscillator (centre) andmixed-down signal (left).

One important property is the exceptionally low level of mi-crowave absorption, which has been exploited for makingvarious passive microwave components. Wireless commu-nication has now emerged as the first large commercial mar-ket for HTS technology two decades after the discovery ofHTS. Active high-frequency devices have also been demon-strated, most of them exploiting the unique features of theAC Josephson effect. We have recently [36]–[38] experi-mentally demonstrated a combined HTS local heterodyneoscillator and mixer based on a resistive-step-edge junctionpair structure (Fig. 12). This device provides heterodyne lo-cal oscillator (LO) output and RF signal down-conversionthat is frequency-tunable. Mixing of microwave frequenciesbetween 1 to 5 GHz and intermediate frequencies (IF) fre-quencies between 100 MHz to 5 GHz were observed [37],[38].

Very recently, we successfully integrated the self-pumped Josephson heterodyne mixer with other HTS pas-sive components (band-pass and low-pass filters) on a singlechip to produce a monolithic microwave integrated circuit(MMIC) HTS frequency down-converter [39], [40]. Thisdemonstration has significant implication for the potentialrealization of a compact, all-HTS integrated front-end re-ceiver for the wireless communication industry. The sameconcepts can also be applied to higher frequency bands suchas THz mixing detectors.

5.2 THz Imaging

HTS broadband Josephson detectors have been developedand applied to millimetre wave (mm-wave) and terahertz


Fig. 13 (Top) A thin-film log-periodic antenna-coupled Josephson de-tector designed for operation at 200–600 GHz; (bottom) Image of leaf ob-tained with 0.6 THz radiation.

(THz) imaging [10], [41], [42], using our standard Joseph-son junction. The optimized high IcRn values of the junc-tion enable a detector that responds well to the specifiedfrequencies at 77 K [41], [42]. Figure 13 shows a thin-film log-periodic antenna-coupled HTS step-edge Joseph-son THz detector, designed for operation at 200–600 GHz[42]. Images at ≈ 200 GHz and ≈ 600 GHz (see Fig. 11)were acquired with the same detector; each demonstratedtheir unique properties [42]. The results demonstrate the po-tential of achieving a cheaper, compact and portable multi-spectral imager based on a HTS detector. Currently, acrycooler-cooled system and array THz detectors are underdevelopment for THz imaging.

6. Conclusion

The step-edge GBJs using thin YBCO films on MgO [100]single-crystal substrates have been developed at CSIRO toachieve a range of parameters that have enabled their use inSQUIDs and other devices for a range of applications. Theuse in the LANDTEM mineral exploration application hasbeen commercially successful and other applications includ-ing UXO detection, THz imaging and microwave compo-nents should also be similarly successful in the future. Thestep-edge technology that is the basis of these devices andapplications is versatile and cost effective to fabricate en-abling easy placement of the junctions on a chip for opti-mized device design and arrays.

Acknowledgments

We wish to acknowledge our many collaborators over theyears. We would like to acknowledge the contribution ofDr. Yuji Miyato, of Osaka University, Japan, for his work oninvestigating the intrinsic noise of CSIRO’s 8 mm SQUIDmagnetometers, shown in Fig. 3.

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[37] J. Du, J.C. Macfarlane, T. Zhang, Y. Cai, and Y.J. Guo, “Self-pumped HTS Josephson heterodyne tuneable mixer,” Supercond.Sci. Technol., vol.25, 025019, 2012.

[38] J. Du, J.C. Macfarlane, C.M. Pegrum, T. Zhang, Y. Cai, and Y.J.Guo, “A Self-pumped HTS Josephson RSQUID mixer: Modellingand measurement,” J. Appl. Phys., vol.111, 053910, 2012.

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[40] T. Zhang, J. Du, Y.J. Guo, and X. Sun, “On-chip integration ofHTS bandpass and lowpass filters with a Josephson mixer,” Elec-tron. Lett., vol.48, no.12, 2012.

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[42] J. Du. A.D. Hellicar, S. Hanham, L. Li, J.C. Macfarlane, K.E.Leslie, and C.P. Foley, “Terahertz and millimetre wave imaging witha broadband Josephson detector working above 77 K,” J. Infrared,Millimeter, and Terahertz Waves, vol.32, pp.681–690, 2011.

[43] P. Schmidt, D. Clark, K.E. Leslie, M. Bick, D. Tilbrook, andC.P. Foley, “GETMAG — A SQUID magnetic tensor gradiometerfor mineral and oil exploration,” Exploration Geophysics, vol.35,pp.297–305, 2004.

Shane T. Keenan is a research scientistwith CSIRO’s Superconducting devices groupbased in Sydney, Australia. He graduated fromGMIT in Ireland with a B.Sc. (Hons) in AppliedPhysics and Instrumentation in 2002 and after ashort period working in the Bio-pharmaceuticalindustry as an instrumentation engineer, he re-turned to university to pursue a Ph.D. in exper-imental physics. In 2008, he earned his Ph.D.from the University of Strathclyde (Glasgow,Scotland) researching and developing mobile

SQUID based detector systems for applications such as non-destructiveevaluation (NDE) and magnetic anomaly detection (MAD). The same year,he took up a post-doc position with CSIRO where his research interests arein developing SQUID based tensor gradiometers for both geophysics andmagnetic anomaly detection such as UXO. Shane has been with the groupfor the past 4 years.

Jia Du received her B.S. from Xidian Uni-versity, China, in 1982, M.S. from University ofElectronic Science and Technology of China in1984, and Ph.D. from the University of Tech-nology, Sydney, Australia, in 1993. She workedas a lecturer at University of Electronic Scienceand Technology of China in 1984–1988, andas a Postdoctoral Research Fellow at NationalInst of Materials and Chemical Research, Japanin 1993–1994. She joined CSIRO in 1995 andhas been working on superconducting electron-

ics since 1997. She is currently a Principal Research Scientist and projectleader. Her primary research interests are in HTS and LTS Josephson junc-tions, SQUIDs, other novel devices and related materials issues. In recentyears, she leads the development of HTS Josephson junction devices formicrowave and terahertz applications.


Emma E. Mitchell received a B.Sc. de-gree (Hons 1A) from Macquarie University in1992 while concurrently working as an exper-imental scientist at CSIRO Food Research onthe biophysics of artificial membranes and or-ganic monolayers. She completed her Ph.D. onlow dimensional semiconductor systems in thequantum limit at the University of NSW in 1997.She joined the CSIRO Division of Materials Sci-ence and Engineering as a research scientist in1997 focusing on the fabrication, characteriza-

tion and physics of high-temperature superconducting Josephson junctionsand SQUIDs. Dr. Mitchell also has expertise in low-Tc superconductingsensors including nanojunctions and coplanar waveguide resonators usingmicrowave spectroscopy, electromagnetic transport and optical measure-ments down to millikelvin temperatures. Dr. Mitchell is a member of theAustralian Institute of Physics.

Simon K. H. Lam received his B.S. (Hons)and Ph.D. degree from University of Technol-ogy, Sydney in 1995 and University of Sydneyin 2000 respectively. He joined the Supercon-ductivity group of CSIRO during his industrialtraining in 1993 and since then working part-time with the same group. He was permanentlyemployed by CSIRO in 2000, working on super-conducting thin film and devices. His researchinterest includes fabrication and characterisationof both low and high temperature superconduct-

ing devices and their applications. Simon is a member of the AustralianInstitute of Physics.

John C. MacFarlane graduated B.Sc.(Hons) in Natural Philosophy from the Univer-sity of Glasgow in 1958, then spent 2 yearsas a Health Physicist with the UK Atomic En-ergy Authority. From 1960–1964 he carriedout research at the University of Strathclyde onthin-film dielectrics, which led to the award ofhis Ph.D. (Glasgow) in 1964. Later that yearhe moved to Sydney, Australia, with his wifeand daughter, to accept an appointment withthe CSIRO as a Research Scientist where he re-

mained for the next 27 years. He returned to the UK in 1992 and workedthere for some 15 years on short-term appointments at Strathclyde, and atthe National Physical Laboratory. In 2009 he retired to Tasmania, Aus-tralia. He is the author or co-author of over 100 peer-reviewed papersmainly in the fields of electrical metrology and superconductivity, and isa Fellow of the Institute of Physics (UK) and the Australian Institute ofPhysics. He still maintains part-time interactions with CSIRO as an Hon-orary Research Fellow.

Chris J. Lewis joined the CSIRO in 1996after spending more than 10 years in the medi-cal electronics industry. He has developed elec-tronics for ground probing radar systems as wellas the LANDTEM superconducting geophysi-cal survey system which won the CSIRO Medalfor Research Achievement in 2007 and the Aus-tralian Institute of Mining and Metallurgy Min-eral Industry Operating Technique Award 2010.Chris has also developed FPGA firmware for theNgara microwave backhaul project which was

awarded the CSIRO Chairman’s medal in 2012. In 2009 Chris was awardeda Bachelor of Engineering with first class honours from the University ofTechnology Sydney where he graduated top of the electrical engineeringcohort. His current activities include the design of high slew rate electron-ics for SQUID readout and ultra wide band radar for geophysics.

Keith E. Leslie current leads CSIRO’s “Su-perconductivity & Magnetism” Group. Underhis leadership, members of this Group were re-sponsible for the development of “LANDTEM”,a three axis, HTS SQUID system that has provenextremely successful for geophysical prospect-ing. LANDTEM has won both an internalCSIRO award for research innovation and theAusIMM 2010 award for “Technological Inno-vation in the Minerals Industry”. Current KeithLeslie leads a number of projects aimed at im-

proving the magnetic anomaly detection, location and classification by us-ing HTS SQUID base tensor gradiometers rather than total field sensors.

Cathy P. Foley is the Chief of CSIRO’sDivision of Materials Science and Engineer-ing. She received her B.Sc. (Hons) Dip. Ed.and Ph.D. from Macquarie University in 1981and 1985, respectively. Before becoming Chief,Cathy was involved in CSIRO’s Superconduct-ing Devices and Applications Project develop-ing superconducting systems for mineral explo-ration, detection of metal for quality assurancein manufacturing, terahertz imaging, and UXOdetection. This multiple million-dollar project

assisted with the discovery and delineation of the BHPB Cannington Silvermine and her team is currently commercialising their systems. Her groupwas the first team to successfully fly superconducting systems. Dr Foleyhas a world-class reputation in her field, being a Fellow of the Institute ofPhysics in the UK and immediate past President of the Australian Instituteof Physics. She is a Fellow of the Academy of Technological Sciencesand Engineering (ASTE) and a member of the Prime Minister’s ScienceEngineering and Innovation Council (PMSEIC).

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