Salvatore PernaTutor: Prof. Claudio Serpico

XXIX Cycle -I year presentation

Nanomagnetism and Spintronics

Salvatore Perna.

I AM A GRADUATE STUDENT IN ELECTRICAL ENGINEERING

… AND AS A PHD STUDENT I’M WORKING ON NANOMAGNETISM AND SPINTRONICS

Salvatore Perna.

Nanomagnetism and Spintronics Study the evolution of the magnetic properties of the ferromagnetic

materials on nanometric scale, in presence of external excitations such as magnetic field or spin-polarized currents

This study involves many theoretical fields :

• Nonlinear dynamical systems• Chaos theory• Statistical mechanics• Stochastic processes• Solid state physics, and so on…

… and is of technological interest for applications regarding :

Magnetic Recording ( optimized memory devices) Information and Comunication Technologies

( oscillators, magnetic logic circuits,…)

Salvatore Perna.

MY RESEARCH ACTIVITIES : Reliability of ultrafast ( sub-nanosecond) switching strategies

• Control of switching probability

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 10.5 11 11.5 120

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1

Hy/hay

ProbabilitàProbability to reach desidered state

Controlling field

Phase-Flow Interpretation of Magnetization Relaxation in NanomagnetsG.Bertotti, ID Mayergoyz, M d'Aquino, S Perna, C SerpicoMagnetics, IEEE Transactions on 50 (11), 1-4, 2014

Salvatore Perna.

MY RESEARCH ACTIVITIES : Reliability of ultrafast ( sub-nanosecond) switching strategies

• Proposed Novel switching strategies

Analysis of Reliable Ultrafast Precessional Switching in the Presence of Transverse Applied Magnetic FieldsM d'Aquino, S Perna, C Serpico, G Bertotti, ID Mayergoyz Magnetics, IEEE Transactions on 50 (11), 1-4, 2014

With exciting magnetic field

With injected spin-polarized current

Analysis of reliable sub-ns spin-torque switching under transverse bias magnetic fieldsM d'Aquino, S Perna, C Serpico, G Bertotti, ID Mayergoyz Magnetics, accepted for publication in the Journal of Applied Physics.

Salvatore Perna.

MY RESEARCH ACTIVITIES : Assisted switching strategy

• Study the effects of the application of microwave excitation

Progressive Basin erosion due to a very low amplitude external microwave excitation close to the calculated threshold value

Heteroclinic tangle phenomena in nanomagnets subject to time-harmonic excitations, C. Serpico, A.Quercia, S. Perna, G.Bertotti, M. d’Aquino and I.D. Mayergoyz, accepted for publications on Journal of Applied Physics.

Salvatore Perna.

MY RESEARCH ACTIVITIES : Assisted switching strategy

• Study the interaction of the magnetic system and the thermal fluctuation due to the finite temperature of the external enviroment

Dependence of the switching fields from the temperature fo the external bath

Noise-induced bifurcations in magnetization dynamics of uniaxial nanomagnets

C Serpico, S Perna, G Bertotti, M d'Aquino, A Quercia, ID Mayergoyz Journal of Applied Physics 117 (17), 17A709, (2015)

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Astroid Field-Temperature

Normalized values of Temperature

Salvatore Perna.

MY RESEARCH ACTIVITIES : Low energy dissipations devices

• Study the switching condition for a compensated anisotropy nanomagnet ( in collaboration with the University of Messina, local reference Prof. Giovanni Finocchio )

The spin-polarized current necessary to activate switching dynamics is one order of magnitude lower.

SWITCHING PROPERTIES OF PERPENDICULAR STT-MRAMs WITH SECOND ORDER ANISOTROPY S. Perna, R. Tomasello, C. Serpico, M. d’Aquino, and G. Finocchio, accepted for presentation for poster presentation at the Intermag 2015 conference.

0 0.5 1 1.5 2 2.5 3 3.5 44

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11

K2 [104 J/m3]

SC

D [1

05 A

/cm

2 ]

K1=0.58 MJ/m3

K1=0.60 MJ/m3

K1=0.56 MJ/m3

Partecipation to Conference1. Oral presentation of the work :

Phase-Flow Interpretation of Magnetization Relaxation in Nanomagnets in IEEE International Magnetics Conference, Dresden ( Germany), May 4-8 ( 2014)

2. Poster presentation of the work : Phase-Flow Interpretation of Magnetization Relaxation in Nanomagnets in ET2014, XXX Riunione Annuale dei Ricercatori in Elettrotecnica , 19-20 June (2014), Sorrento ( Italy).

3. Oral Presentation of the work : Noise-induced bifurcations in magnetization dynamics of uniaxial nanomagnets in Magnet 2015, the 4th italian conference on magnetism, Bologna (Italy), February 17-19 , (2015).

4. Poster presentation of the work : Analysis of reliable sub-ns spin-torque switching under transverse bias magnetic fields, in Magnet 2015, the 4th italian conference on magnetism, Bologna (Italy), February 17-19 , (2015).

Salvatore Perna.

Salvatore Perna.

SUMMARY OF THE FIRST YEAR ACTIVITIES

Credits year 1

  1 2 3 4 5 6  

Estimated

bimonth

bimonth

bimonth

bimonth

bimonth

bimonth

Summary

Modules 20  3        3

Seminars 50.2 0.4   0.2   1.7 2.5

Research 35 10 6.5 10 10 10 1054.5

60            60

Salvatore Perna.

SECOND YEAR ACTIVITIES PLANI. From 1° April to 31 July i will work at the University of Salamanca with Prof. Luis Lopez

Diaz and doctor Eduardo Martinez ( Department of Applied Physics) on the dynamics of coupled multidimensional magnetic structures ( magnetic vortices ).

II. Modules Ad Hoc : 24 Credits• Elettromagnetismo e Relatività ( Prof. Amedeo Capozzoli)• Dinamica Non Lineare I e II ( Prof. Claudio Serpico e Prof. Mario Di Bernardo)• Complementi di Analisi Funzionale ( Prof. Renato Fiorenza) • Micromagnetics ( Prof. Claudio Serpico )

III. Seminars : 5 Credits

IV. Teaching Activity : 10 Credits

V. Research Activities : 45 Credits

Salvatore Perna.

THANK YOURFOR

YOUR ATTENTION !!!