Overview

­­

Research Highlights:

Adding new functionality to devices, which often requires precise control at the nanoscale, has always been a driving force in research. In a collaboration with scientists at the Paul Scherrer Institute (PSI) and the ETH Zurich, Switzerland and Manchester, UK, we have found a new way to locally switch the orientation of a magnetic feature that is smaller than 20 nm. This discovery provides added control for future technological applications such as data processing, microwave sources or magnetic sensors.

For details see: 

P. Wohlhüter, M.T. Bryan, P. Warnicke, S. Gliga, S.E. Stevenson, G. Heldt, L. Saharan, A.K. Suszka, C. Moutafis, R.V. Chopdekar, J. Raabe, T. Thomson, G. Hrkac, L.J. Heyderman, "Nanoscale switch for vortex polarization mediated by Bloch core formation in magnetic hybrid systems." Nat. Commun. 6, 7836 (2015)

http://www.nature.com/ncomms/2015/150804/ncomms8836/full/ncomms8836.html

https://www.youtube.com/watch?v=sdDjS6KMQLQ&feature=youtu.be

Background

I completed my PhD in the Department of Solid State Physics, Vienna University of Technology in 2005, studying eddy current effects in magnetic nanomaterials and the­ir influence on high frequency magnetisation behaviour. ­

­2005 I joined the Department of engineering Materials at the University of Sheffield. I was developing a finite element model to treat non linear magnetisation dynamics to investigate high frequency switching and spin torque effects in magnetic nano pillars and magnetic Tunnel Junction systems.

In 2009 I was awarded the Royal Society University Research Fellowship and the WWTF High Potential Award from the Vienna Science and technology Fund.

In 2012 I joined the University of Exeter as an associate Professor in Functional Materials.

In December 2016 Awarded Personal Chair in Applied theoretical and computational Solid-state physics

Research interests

My main research area is computational and theoretical magnetism, and especially the development of a numerical model to investigate and predict the behaviour of magnetic spin valve systems and the effect of eddy currents in nano-scale materials. In particular I am working on the theoretical and numerical description of spin electronic devices on a length scale ranging from the computation of the local spin current density and magnetization dynamics with a sub-nm resolution in micron size devices (magnetic nano pillars and Magnetic Tunnel Junctions).

A prominent example for my work is the theoretical explanation of the angular dependency of phase locking phenomena in point contacted spin valves and my work on the simulation of spin current induced magnetization dynamics that explained the low frequency oscillations found in point contact devices that were explained by vortex oscillations.

My latest research includes ab initio simulations of atomic structures, solid state molecular dynamics for the simulation of the transition of amorphous to crystalline grain boundaries in NdFeB magnets within the framework of an industrial funded project on permanent magnets (European-Japanese consortium) and the coupling of the spin-diffusion equation with the Landau-Lifshitz-Gilbert equation.

Key projects

• EPSRC Heat induced phase change exchange coupled composite media (HIP-ECC) Joint Project with Prof Thomson, University of Manchester

• Royal Society University Research Fellowship, Fundamentals of spin-torque induced magnetisation dynamics

• WWTF, Micromagnetic Simulations and Computational Design of Future Devices

• Toyota Motor Corporation, Fundamental understanding of boundary phases between magnetic grains in permanent magnets

• EPSRC Bridging the Gaps, Pump-Priming Award,Ferrofluid-based microscale dosage device

• COST Action P19 Multiscale modelling of Materials

• BRITISH-ITALIAN PARTNERSHIP PROGRAMME, Nanotechnology: Programmable Lab on a Chip

Research group

• Dr Lalita Saharan (Senior research fellow)

• Dr Matthew Bryan (Senior research fellow)

• Dr Thomas Ostler (Senior research fellow)

Former Research group members:

• Dr Rene Dost (Senior research fellow)

• Mr Alexander Steiner (Student)

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Publications

_{Copyright Notice: Any articles made available for download are for personal use only. Any other use requires prior permission of the author and the copyright holder.}

| 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 | 2014 | 2013 | 2012 | 2011 | 2010 | 2009 | 2008 | 2007 | 2006 | 2005 | 2003 |

2022

• Skelland C, Hrkac G. (2022) Surface Energy Driven Grain Growth Model: FePt L10 Nanoparticles, DOI:10.48550/arxiv.2209.05966.
• Skelland C, Hrkac G. (2022) Surface Energy Driven Grain Growth Model: FePt L10 Nanoparticles. [PDF]

2021

• Cuadrado R, Evans RFL, Shoji T, Yano M, Kato A, Ito M, Hrkac G, Schrefl T, Chantrell RW. (2021) First principles and atomistic calculation of the magnetic anisotropy of Y₂Fe₁₄B, JOURNAL OF APPLIED PHYSICS, volume 130, no. 2, article no. ARTN 023901, DOI:10.1063/5.0053950. [PDF]
• Ener S, Skokov KP, Palanisamy D, Devillers T, Fischbacher J, Eslava GG, Maccari F, Schäfer L, Diop LVB, Radulov I. (2021) Twins – A weak link in the magnetic hardening of ThMn12-type permanent magnets, Acta Materialia, volume 214, DOI:10.1016/j.actamat.2021.116968.

2020

• Kirk E, Bull C, Finizio S, Sepehri-Amin H, Wintz S, Suszka AK, Bingham NS, Warnicke P, Hono K, Nutter PW. (2020) Anisotropy induced spin re-orientation in chemically-modulated amorphous ferrimagnetic films, DOI:10.48550/arxiv.2007.03657.
• Da Browski M, Frisk A, Burn DM, Newman DG, Klewe C, N'Diaye AT, Shafer P, Arenholz E, Bowden GJ, Hesjedal T. (2020) Optically and Microwave-Induced Magnetization Precession in [Co/Pt]/NiFe Exchange Springs, ACS Appl Mater Interfaces, volume 12, no. 46, pages 52116-52124, DOI:10.1021/acsami.0c14058. [PDF]
• Kirk E, Bull C, Finizio S, Sepehri-Amin H, Wintz S, Suszka AK, Bingham NS, Warnicke P, Hono K, Nutter PW. (2020) Anisotropy induced spin re-orientation in chemically-modulated amorphous ferrimagnetic films, Physical Review Materials, volume 4, DOI:10.1103/PhysRevMaterials.4.074403. [PDF]
• Westmoreland SC, Skelland C, Shoji T, Yano M, Kato A, Ito M, Hrkac G, Schrefl T, Evans RFL, Chantrell RW. (2020) Atomistic simulations of α - Fe /Nd2Fe14B magnetic core/shell nanocomposites with enhanced energy product for high temperature permanent magnet applications, Journal of Applied Physics, volume 127, no. 13, DOI:10.1063/1.5126327.
• Skelland C, Westmoreland SC, Ostler T, Evans RFL, Chantrell RW, Yano M, Shoji T, Kato A, Ito M, Winklhofer M. (2020) Atomistic study on the pressure dependence of the melting point of NdFe₁₂, AIP ADVANCES, volume 10, no. 2, DOI:10.1063/1.5130450. [PDF]

2019

• Skelland C, Ostler T, Westmoreland SC, Evans REL, Chantrell RW, Yano M, Shoji T, Kato A, Winklhofer M, Zimanyi G. (2019) The Effect of Interstitial Nitrogen Addition on the Structural Properties of Supercells of NdFe_12-xTi_x, IEEE TRANSACTIONS ON MAGNETICS, volume 55, no. 10, article no. ARTN 6700205, DOI:10.1109/TMAG.2019.2920214. [PDF]

2018

• Skelland C, Ostler T, Westland S, Evans R, Chantrell R, Yano M, Shoji T, Manabe A, Kato A, Winklhofer M. (2018) Probability distribution of substituted Titanium in RT12 (R = Nd, Sm, T = Fe, Co) structures, DOI:10.48550/arxiv.1804.05608.
• Pfeiler C-M, Ruggeri M, Stiftner B, Exl L, Hochsteger M, Hrkac G, Schöberl J, Mauser NJ, Praetorius D. (2018) Computational micromagnetics with Commics, DOI:10.48550/arxiv.1812.05931.
• Exl L, Fischbacher J, Kovacs A, Oezelt H, Gusenbauer M, Yokota K, Shoji T, Hrkac G, Schrefl T. (2018) Magnetic microstructure machine learning analysis, DOI:10.48550/arxiv.1808.03794.
• Pfeiler C-M, Ruggeri M, Stiftner B, Exl L, Hochsteger M, Hrkac G, Schöberl J, Mauser NJ, Praetorius D. (2018) Computational micromagnetics with Commics, Computer Physics Communications, 248 (2020), 106965. [PDF]
• Exl L, Fischbacher J, Kovacs A, Oezelt H, Gusenbauer M, Yokota K, Shoji T, Hrkac G, Schrefl T. (2018) Magnetic microstructure machine learning analysis, J. Phys. Mater, volume 2. [PDF]
• Westmoreland SC, Evans RFL, Hrkac G, Schrefl T, Zimanyi GT, Winklhofer M, Sakuma N, Yano M, Kato A, Shoji T. (2018) Reprint of Multiscale model approaches to the design of advanced permanent magnets, Scripta Materialia, volume 154, pages 266-272, DOI:10.1016/j.scriptamat.2018.04.019.
• Skelland C, Ostler T, Westland S, Evans R, Chantrell R, Yano M, Shoji T, Manabe A, Kato A, Winklhofer M. (2018) Probability distribution of substituted Titanium in RT12 (R = Nd, Sm, T = Fe, Co) structures. [PDF]
• Cuadrado R, Oroszlány L, Szunyogh L, Hrkac G, Chantrell RW, Ostler TA. (2018) A multiscale model of the effect of Ir thickness on the static and dynamic properties of Fe/Ir/Fe films, Sci Rep, volume 8, no. 1, DOI:10.1038/s41598-018-21934-5. [PDF]
• Westmoreland SC, Evans RFL, Hrkac G, Schrefl T, Zimanyi GT, Winklhofer M, Sakuma N, Yano M, Kato A, Shoji T. (2018) Multiscale model approaches to the design of advanced permanent magnets, Scripta Materialia, volume 148, pages 56-62, DOI:10.1016/j.scriptamat.2018.01.019.

2017

• Hrkac G, Pfeiler C-M, Praetorius D, Ruggeri M, Segatti A, Stiftner B. (2017) Convergent tangent plane integrators for the simulation of chiral magnetic skyrmion dynamics, DOI:10.48550/arxiv.1712.03795.
• Fischbacher J, Kovacs A, Oezelt H, Gusenbauer M, Schrefl T, Exl L, Givord D, Dempsey NM, Zimanyi G, Winklhofer M. (2017) On the limits of coercivity in permanent magnets, DOI:10.48550/arxiv.1708.01880.
• Kruglyak VV, Davies CS, Au Y, Mushenok FB, Hrkac G, Whitehead NJ, Horsley SAR, Philbin TG, Poimanov VD, Dost R. (2017) Graded Magnonic Index and Spin Wave Fano Resonances in Magnetic Structures: Excite, Direct, Capture, Spin Wave Confinement, Taylor & Francis, 11-46, DOI:10.1201/9781315110820-2.
• Mushenok FB, Dost R, Davies CS, Allwood DA, Inkson BJ, Hrkac G, Kruglyak VV. (2017) Broadband conversion of microwaves into propagating spin waves in patterned magnetic structures, DOI:10.48550/arxiv.1706.04409.
• Kruglyak VV, Davies CS, Au Y, Mushenok FB, Hrkac G, Whitehead N, Horsley SAR, Philbin TG, Poimanov VD, Dost R. (2017) Graded Magnonic Index And Spin-Wave Fano Resonances, Spin Wave Confinement: Propagating Waves, Pan Stanford Publishing Pte. Ltd, 11-46.
• Hrkac G, Pfeiler C-M, Praetorius D, Ruggeri M, Segatti A, Stiftner B. (2017) Convergent tangent plane integrators for the simulation of chiral magnetic skyrmion dynamics, Advances in Computational Mathematics, 45 (2019), 1329-1368. [PDF]
• Gliga S, Hrkac G, Donnelly C, Büchi J, Kleibert A, Cui J, Farhan A, Kirk E, Chopdekar RV, Masaki Y. (2017) Emergent dynamic chirality in a thermally driven artificial spin ratchet, Nat Mater, volume 16, no. 11, pages 1106-1111, DOI:10.1038/nmat5007. [PDF]
• Fischbacher J, Kovacs A, Oezelt H, Gusenbauer M, Schrefl T, Exl L, Givord D, Dempsey NM, Zimanyi G, Winklhofer M. (2017) On the limits of coercivity in permanent magnets, Appl. Phys. Lett, volume 111. [PDF]
• Mushenok FB, Dost R, Davies CS, Allwood DA, Inkson BJ, Hrkac G, Kruglyak VV. (2017) Broadband conversion of microwaves into propagating spin waves in patterned magnetic structures, Appl. Phys. Lett, volume 111. [PDF]
• Sepehri-Amin H, Iwama H, Hrkac G, Butler KT, Shima T, Hono K. (2017) Pt surface segregation in L10-FePt nano-grains, Scripta Materialia, volume 135, pages 88-91, DOI:10.1016/j.scriptamat.2017.03.035.
• Barton CW, Ostler TA, Huskisson D, Kinane CJ, Haigh SJ, Hrkac G, Thomson T. (2017) Substrate Induced Strain Field in FeRh Epilayers Grown on Single Crystal MgO (001) Substrates, Sci Rep, volume 7, DOI:10.1038/srep44397. [PDF]
• Ostler TA, Barton C, Thomson T, Hrkac G. (2017) Modeling the thickness dependence of the magnetic phase transition temperature in thin FeRh films, Physical Review B, volume 95, no. 6, DOI:10.1103/PhysRevB.95.064415.

2016

• Bance S, Oezelt H, Schrefl T, Ciuta G, Dempsey NM, Givord D, Winklhofer M, Hrkac G, Zimanyi G, Gutfleisch O. (2016) Influence of defect thickness on the angular dependence of coercivity in rare-earth permanent magnets, DOI:10.48550/arxiv.1603.08248.
• Bance S, Seebacher B, Schrefl T, Exl L, Winklhofer M, Hrkac G, Zimanyi G, Shoji T, Yano M, Sakuma N. (2016) Grain-size dependent demagnetizing factors in permanent magnets, DOI:10.48550/arxiv.1603.08239.
• Keatley PS, Sani SR, Hrkac G, Mohseni SM, Dürrenfeld P, Åkerman J, Hicken RJ. (2016) Super-harmonic injection locking of nano-contact spin-torque vortex oscillators, DOI:10.48550/arxiv.1604.04462.
• Keatley PS, Sani SR, Hrkac G, Mohseni SM, Dürrenfeld P, Loughran THJ, Åkerman J, Hicken RJ. (2016) Direct observation of magnetization dynamics generated by nano-contact spin-torque vortex oscillators, DOI:10.48550/arxiv.1604.04455.
• Bryan MT, Heldt G, Thomson T, Heyderman LJ, Hrkac G. (2016) Complex spin configurations in hybrid magnetic multilayer structures due to mutual spin imprinting, PHYSICAL REVIEW B, volume 94, no. 10, article no. ARTN 104415, DOI:10.1103/PhysRevB.94.104415. [PDF]
• Keatley PS, Sani SR, Hrkac G, Mohseni SM, Dürrenfeld P, Åkerman J, Hicken RJ. (2016) Superharmonic injection locking of nanocontact spin-torque vortex oscillators, Physical Review B, volume 94, no. 9, DOI:10.1103/PhysRevB.94.094404.
• Keatley PS, Sani SR, Hrkac G, Mohseni SM, Dürrenfeld P, Loughran THJ, Åkerman J, Hicken RJ. (2016) Direct observation of magnetization dynamics generated by nanocontact spin-torque vortex oscillators, Physical Review B, volume 94, no. 6, DOI:10.1103/PhysRevB.94.060402.
• Ruggeri M, Abert C, Hrkac G, Suess D, Praetorius D. (2016) Coupling of dynamical micromagnetism and a stationary spin drift-diffusion equation: A step towards a fully self-consistent spintronics framework, Physica B: Condensed Matter, volume 486, pages 88-91, DOI:10.1016/j.physb.2015.09.003.

2015

• Bance S, Ciuta G, Shoji T, Gao T, Hrkac G, Yano M, Manabe A, Dempsey NM, Schrefl T, Givord D. (2015) Hard magnet coercivity, DOI:10.48550/arxiv.1502.02491.
• Bartolucci C, Ravagli E, Bucchi A, Baruscotti M, DiFrancesco D, Severi S. (2015) Rate-adapted Dynamic-clamp of the Funny Current in Sinoatrial Pacemaker Cells, 2015 COMPUTING IN CARDIOLOGY CONFERENCE (CINC), volume 42, pages 1-4. [PDF]
• Hrkac G, Keatley PS, Bryan MT, Butler K. (2015) Magnetic vortex oscillators, Journal of Physics D: Applied Physics, volume 48, no. 45, DOI:10.1088/0022-3727/48/45/453001.
• Barton CW, Saharan L, Hrkac G, Thomson T. (2015) Effect of Fe under layer in ultrathin FeRh films, 2015 IEEE International Magnetics Conference, INTERMAG 2015, DOI:10.1109/INTMAG.2015.7157518.
• Keatley PS, Sani S, Hrkac G, Mohseni S, Durrenfeld P, Åkerman J, Hicken R. (2015) Magneto-optical observation of mutual phase-locking in a pair of spin-torque vortex oscillators, 2015 IEEE International Magnetics Conference, INTERMAG 2015, DOI:10.1109/INTMAG.2015.7156846.
• Wohlhüter P, Bryan MT, Warnicke P, Gliga S, Stevenson SE, Heldt G, Saharan L, Suszka AK, Moutafis C, Chopdekar RV. (2015) Nanoscale switch for vortex polarization mediated by Bloch core formation in magnetic hybrid systems, Nat Commun, volume 6, DOI:10.1038/ncomms8836. [PDF]
• Abert C, Ruggeri M, Bruckner F, Vogler C, Hrkac G, Praetorius D, Suess D. (2015) A three-dimensional spin-diffusion model for micromagnetics, Scientific Reports, volume 5, article no. 14855. [PDF]

2014

• Abert C, Ruggeri M, Bruckner F, Vogler C, Hrkac G, Praetorius D, Suess D. (2014) A three-dimensional spin-diffusion model for micromagnetics, DOI:10.48550/arxiv.1410.6067.
• Abert C, Hrkac G, Page M, Praetorius D, Ruggeri M, Suess D. (2014) Spin-polarized transport in ferromagnetic multilayers: An unconditionally convergent FEM integrator, DOI:10.48550/arxiv.1402.0983.
• Bance S, Ciuta G, Shoji T, Gao T, Hrkac G, Yano M, Manabe A, Dempsey NM, Schrefl T, Givord D. (2014) Hard magnet coercivity, Proceedings of the 23rd International Workshop on Rare earth and Future Permanent Magnets and Their Appications (REPM2014), Annapolis, Maryland, August 2014. [PDF]
• Bance S, Seebacher B, Schrefl T, Exl L, Winklhofer M, Hrkac G, Zimanyi G, Shoji T, Yano M, Sakuma N. (2014) Grain-size dependent demagnetizing factors in permanent magnets, Journal of Applied Physics, volume 116, no. 23, DOI:10.1063/1.4904854.
• Bance S, Oezelt H, Schrefl T, Winklhofer M, Hrkac G, Zimanyi G, Gutfleisch O, Evans RFL, Chantrell RW, Shoji T. (2014) High energy product in Battenberg structured magnets, APPLIED PHYSICS LETTERS, volume 105, no. 19, article no. ARTN 192401, DOI:10.1063/1.4897645. [PDF]
• Huber T, Bergmair B, Vogler C, Bruckner F, Breth L, Hetaba W, Hrkac G, Suess D. (2014) Ultra-Low-Cost RFID Based on Soft Magnetic Ribbons, IEEE TRANSACTIONS ON MAGNETICS, volume 50, no. 10, article no. ARTN 4004905, DOI:10.1109/TMAG.2014.2327200. [PDF]
• Abert C, Hrkac G, Page M, Praetorius D, Ruggeri M, Suess D. (2014) Spin-polarized transport in ferromagnetic multilayers: An unconditionally convergent FEM integrator, Computers and Mathematics with Applications, volume 68, no. 6, pages 639-654, DOI:10.1016/j.camwa.2014.07.010.
• Hrkac G, Butler K, Woodcock TG, Saharan L, Schrefl T, Gutfleisch O. (2014) Modeling of Nd-oxide grain boundary phases in Nd-Fe-B sintered magnets, JOM, volume 66, no. 7, pages 1138-1143, DOI:10.1007/s11837-014-0980-5.
• Woodcock TG, Ramasse QM, Hrkac G, Shoji T, Yano M, Kato A, Gutfleisch O. (2014) Atomic-scale features of phase boundaries in hot deformed Nd-Fe-Co-B-Ga magnets infiltrated with a Nd-Cu eutectic liquid, Acta Materialia, volume 77, pages 111-124, DOI:10.1016/j.actamat.2014.05.045.
• Saiden NM, Schrefl T, Davies HA, Hrkac G. (2014) Micromagnetic finite element simulation of nanocrystalline α-Fe/Nd2Fe14B/Fe3B magnets, Journal of Magnetism and Magnetic Materials, volume 365, pages 45-50, DOI:10.1016/j.jmmm.2014.02.073.
• Heldt G, Bryan MT, Hrkac G, Stevenson SE, Chopdekar RV, Raabe J, Thomson T, Heyderman LJ. (2014) Topologically confined vortex oscillations in hybrid [Co/Pd] 8-Permalloy structures, Applied Physics Letters, volume 104, no. 18, DOI:10.1063/1.4873937.
• Bance S, Oezelt H, Schrefl T, Ciuta G, Dempsey NM, Givord D, Winklhofer M, Hrkac G, Zimanyi G, Gutfleisch O. (2014) Influence of defect thickness on the angular dependence of coercivity in rare-earth permanent magnets, Applied Physics Letters, volume 104, no. 18, DOI:10.1063/1.4876451.
• Hrkac G, Woodcock TG, Butler KT, Saharan L, Bryan MT, Schrefl T, Gutfleisch O. (2014) Impact of different Nd-rich crystal-phases on the coercivity of Nd-Fe-B grain ensembles, Scripta Materialia, volume 70, no. 1, pages 35-38, DOI:10.1016/j.scriptamat.2013.08.029.

2013

• Morrison C, Saharan L, Ikeda Y, Takano K, Hrkac G, Thomson T. (2013) Quantifying exchange coupling in segregated granular materials, Journal of Physics D: Applied Physics, volume 46, no. 47, DOI:10.1088/0022-3727/46/47/475002.
• Saharan L, Morrison C, Miles JJ, Thomson T, Schrefl T, Hrkac G. (2013) Modelling interfacial coupling in thin film magnetic exchange springs at finite temperature, Journal of Applied Physics, volume 114, no. 15, DOI:10.1063/1.4826365.
• Saharan L, Morrison C, Ikeda Y, Takano K, Miles JJ, Thomson T, Schrefl T, Hrkac G. (2013) Grain boundaries in granular materials-A fundamental limit for thermal stability, Applied Physics Letters, volume 102, no. 14, DOI:10.1063/1.4801316.
• Reichel F, Schrefl T, Suess D, Hrkac G, Praetorius D, Gusenbauer M, Bance S, Oezelt H, Fischbacher J, Exl L. (2013) Mechanical oscillations of magnetic strips under the influence of external field, EPJ Web of Conferences, volume 40, DOI:10.1051/epjconf/20134013004.

2012

• Goldenits P, Hrkac G, Praetorius D, Suess D. (2012) An Effective Integrator for the Landau-Lifshitz-Gilbert Equation, IFAC-PapersOnLine, volume 45, no. 2, pages 493-497, DOI:10.3182/20120215-3-at-3016.00086.
• Goncharov A, Hrkac G, Dean J, Schrefl T. (2012) Finite Element Modelling of Impedance Spectroscopy Data in Composite Electroceramics, DOI:10.48550/arxiv.1209.3888.
• Hrkac G, Hahn D, Saharan L, Schrefl T, Kim JV, Devolder T, Chappert C. (2012) Magnetic vortex core oscillations in multi point contact spin valve stacks, IEEE Transactions on Magnetics, volume 48, no. 11, pages 3811-3813, DOI:10.1109/TMAG.2012.2195301.
• Goncharov A, Hrkac G, Dean J, Schrefl T. (2012) Finite Element Modelling of Impedance Spectroscopy Data in Composite Electroceramics. [PDF]
• Huber T, Bergmair B, Vogler C, Bruckner F, Hrkac G, Suess D. (2012) Magnetoelastic resonance sensor for remote strain measurements, Applied Physics Letters, volume 101, no. 4, DOI:10.1063/1.4735340.
• Woodcock TG, Zhang Y, Hrkac G, Ciuta G, Dempsey NM, Schrefl T, Gutfleisch O, Givord D. (2012) Understanding the microstructure and coercivity of high performance NdFeB-based magnets, Scripta Materialia, volume 67, no. 6, pages 536-541, DOI:10.1016/j.scriptamat.2012.05.038.
• Woodcock TG, Zhang Y, Hrkac G, Ciuta G, Dempsey NM, Schrefl T, Gutfleisch O, Givord D. (2012) Understanding the microstructure and coercivity of high performance NdFeB-based magnets, Scripta Materialia.
• Bashir MA, Schrefl T, Dean J, Goncharov A, Hrkac G, Allwood DA, Suess D. (2012) Head and bit patterned media optimization at areal densities of 2.5 Tbit/in² and beyond, Journal of Magnetism and Magnetic Materials, volume 324, no. 3, pages 269-275, DOI:10.1016/j.jmmm.2010.11.081.

2011

• Betancourt I, Hrkac G, Schrefl T. (2011) Magnetic domain structure and magnetization reversal in amorphous microwires with circular anisotropy: A micromagnetic approach, Journal of Applied Physics, volume 109, no. 1, DOI:10.1063/1.3525564.
• Kohn A, Dean J, Kovacs A, Zeltser A, Carey MJ, Geiger D, Hrkac G, Schrefl T, Allwood D. (2011) Exchange-bias in amorphous ferromagnetic and polycrystalline antiferromagnetic bilayers: Structural study and micromagnetic modeling, Journal of Applied Physics, volume 109, no. 8, DOI:10.1063/1.3559261.
• Betancourt I, Hrkac G, Schrefl T. (2011) Micromagnetic study of magnetic domain structure and magnetization reversal in amorphous wires with circular anisotropy, Journal of Magnetism and Magnetic Materials, volume 323, no. 9, pages 1134-1139, DOI:10.1016/j.jmmm.2010.11.089.
• Dean J, Bryan MT, Morley NA, Hrkac G, Javed A, Gibbs MRJ, Allwood DA. (2011) Numerical study of the effective magnetocrystalline anisotropy and magnetostriction in polycrystalline FeGa films, Journal of Applied Physics, volume 110, no. 4, DOI:10.1063/1.3618684.
• Morrison C, Saharan L, Hrkac G, Schrefl T, Ikeda Y, Takano K, Miles JJ, Thomson T. (2011) Inter/intra granular exchange and thermal activation in nanoscale granular magnetic materials, Applied Physics Letters, volume 99, no. 13, DOI:10.1063/1.3644469.
• Dean J, Kohn A, Kovács A, Zeltser A, Carey MJ, Hrkac G, Allwood DA, Schrefl T. (2011) The formation mechanism of 360 domain walls in exchange-biased polycrystalline ferromagnetic films, Journal of Applied Physics, volume 110, no. 7, DOI:10.1063/1.3642982.
• Saharan L, Morrison C, Miles JJ, Thomson T, Schrefl T, Hrkac G. (2011) Angle dependence of the switching field of recording media at finite temperatures, Journal of Applied Physics, volume 110, no. 10, DOI:10.1063/1.3662919.
• Hrkac G, Dean J, Allwood DA. (2011) Nanowire spintronics for storage class memories and logic, Philos Trans A Math Phys Eng Sci, volume 369, no. 1948, pages 3214-3228, DOI:10.1098/rsta.2011.0138. [PDF]

2010

• Hrkac G, Goncharov A, Dean J, Schrefl T, Kim JV, Devolder T, Chappert C, Cornelissen S, Van Roy W, Lagae L. (2010) Influence of oscillation modes on the line width of rf emissions in MgO based nanopillars, Journal of Applied Physics, volume 108, no. 2, DOI:10.1063/1.3456497.
• Dean J, Bryan MT, Hrkac G, Goncharov A, Freeman CL, Bashir MA, Schrefl T, Allwood DA. (2010) The incorporation of the Cauchy stress matrix tensor in micromagnetic simulations, Journal of Applied Physics, volume 108, no. 7, DOI:10.1063/1.3489969.
• Hrkac G, Woodcock TG, Freeman C, Goncharov A, Dean J, Schrefl T, Gutfleisch O. (2010) The role of local anisotropy profiles at grain boundaries on the coercivity of Nd2Fe14B magnets, Applied Physics Letters, volume 97, no. 23, DOI:10.1063/1.3519906.
• Dean J, Kovacs A, Kohn A, Goncharov A, Bashir MA, Hrkac G, Allwood DA, Schrefl T. (2010) Exchange bias interactions in polycrystalline/amorphous bilayers, Applied Physics Letters, volume 96, no. 7, DOI:10.1063/1.3294637.
• Goncharov AV, Hrkac G, Dean JS, Schrefl T. (2010) Kronecker product approximation of demagnetizing tensors for micromagnetics, Journal of Computational Physics, volume 229, no. 7, pages 2544-2549, DOI:10.1016/j.jcp.2009.12.004.

2009

• Manfrini M, Devolder T, Kim J-V, Crozat P, Zerounian N, Chappert C, Van Roy W, Lagae L, Hrkac G, Schrefl T. (2009) Agility of vortex-based nanocontact spin torque oscillators, DOI:10.48550/arxiv.0910.1941.
• van Kampen M, Lagae L, Hrkac G, Schrefl T, Kim J-V, Devolder T, Chappert C. (2009) Current-driven vortex oscillations in metallic nanocontacts: Zero-field oscillations and training effects, DOI:10.48550/arxiv.0906.0878.
• Winkler G, Suess D, Lee J, Fidler J, Bashir MA, Dean J, Goncharov A, Hrkac G, Bance S, Schrefl T. (2009) Microwave-assisted three-dimensional multilayer magnetic recording, Applied Physics Letters, volume 94, no. 23, DOI:10.1063/1.3152293.
• Devolder T, Kim JV, Crozat P, Chappert C, Manfrini M, Van Kampen M, Van Roy W, Lagae L, Hrkac G, Schrefl T. (2009) Time-resolved zero field vortex oscillations in point contacts, Applied Physics Letters, volume 95, no. 1, DOI:10.1063/1.3170234.
• Bashir MA, Schrefl T, Suess D, Dean J, Goncharov A, Hrkac G, Belkadi M, Allwood DA, Fidler J. (2009) Exchange coupled bit patterned media under the influence of RF-field pulses, IEEE Transactions on Magnetics, volume 45, no. 10, pages 3851-3854, DOI:10.1109/TMAG.2009.2023621.
• Dean JS, Bryan MT, Allwood DA, Bance S, Bashir MA, Hrkac G, Goncharov A, Schrerl T. (2009) Tailoring domain-wall dynamics with uniaxial anisotropy in nanowires, IEEE Transactions on Magnetics, volume 45, no. 10, pages 4067-4069, DOI:10.1109/TMAG.2009.2023997.
• Devolder T, Kim JV, Manfrini M, Hrkac G, Crozat P, Lagae L, Schrefl T, Chappert C. (2009) Experimental study of current-driven vortex oscillations in magnetic nanocontacts, Proceedings of SPIE - The International Society for Optical Engineering, volume 7398, DOI:10.1117/12.826879.
• Manfrini M, Devolder T, Kim JV, Crozat P, Zerounian N, Chappert C, Van Roy W, Lagae L, Hrkac G, Schrefl T. (2009) Agility of vortex-based nanocontact spin torque oscillators, Applied Physics Letters, volume 95, no. 19, DOI:10.1063/1.3263727.
• Van Kampen M, Lagae L, Hrkac G, Schrefl T, Kim JV, Devolder T, Chappert C. (2009) Current-driven vortex oscillations in metallic nanocontacts: Zero-field oscillations and training effects, Journal of Physics D: Applied Physics, volume 42, no. 24, DOI:10.1088/0022-3727/42/24/245001.
• Cornelissen S, Bianchini L, Hrkac G, Op De Beeck M, Lagae L, Kim JV, Devolder T, Crozat P, Chappert C, Schrefl T. (2009) Auto-oscillation threshold and line narrowing in MgO-based spin-torque oscillators, EPL, volume 87, no. 5, DOI:10.1209/0295-5075/87/57001.
• Hrkac G, Schrefl T, Dean J, Goncharov A, Bance S, Suess D, Fidler J. (2009) Internal effective field sources for spin torque nanopillar oscillators, Journal of Applied Physics, volume 105, no. 5, DOI:10.1063/1.3081646.
• Hrkac G, Schrefl T, Dean J, Goncharov A, Bance S, Allwood D, Suess D, Fidler J. (2009) Micromagnetics of single and double point contact spin torque oscillators, Journal of Applied Physics, volume 105, no. 8, DOI:10.1063/1.3110185.

2008

• Hrkac G, Dean J, Goncharov A, Bance S, Allwood D, Schrefl T, Suess D, Fidler J. (2008) Micromagnetics of single and double point contact spin torque oscillators, DOI:10.48550/arxiv.0804.2119.
• Hrkac G, Schrefl T, Dean J, Goncharov A, Bance S, Suess D, Fidler J. (2008) Internal effective field sources for spin torque nano pillar oscillators, DOI:10.48550/arxiv.0809.4973.
• Cornelissen S, Bianchini L, Hrkac G, de Beeck MO, Lagae L, Kim J-V, Devolder T, Crozat P, Chappert C, Schrefl T. (2008) Auto-oscillation threshold and line narrowing in MgO-based spin-torque oscillators, DOI:10.48550/arxiv.0810.1110.
• Schrefl T, Hrkac G, Goncharov A, Dean J, Bance S, Bashir MA, Suess D. (2008) Finite element/boundary element simulation of future hard disk recording, COMPUTATIONAL METHODS AND APPLIED COMPUTING, pages 430-+. [PDF]
• Betancourt I, Hrkac G, Schrefl T. (2008) Micromagnetic simulation of domain wall dynamics in Permalloy nanotubes at high frequencies, Journal of Applied Physics, volume 104, no. 2, DOI:10.1063/1.2960480.
• Bashir MA, Schrefl T, Dean J, Goncharov A, Hrkac G, Bance S, Allwood D, Suess D. (2008) Microwave-assisted magnetization reversal in exchange spring media, IEEE Transactions on Magnetics, volume 44, no. 11 PART 2, pages 3519-3522, DOI:10.1109/TMAG.2008.2002601.
• Goncharov AV, Schrefl T, Hrkac G, Bance S. (2008) Effect of shields in perpendicular recording, Physica B: Condensed Matter, volume 403, no. 2-3, pages 278-281, DOI:10.1016/j.physb.2007.08.028.
• Dean J, Bashir MA, Goncharov A, Hrkac G, Bance S, Schrefl T, Cazacu A, Gubbins M, Lamberton RW, Suess D. (2008) Thermally induced adjacent track erasure in exchange spring media, Applied Physics Letters, volume 92, no. 14, DOI:10.1063/1.2905292.
• Bance S, Schrefl T, Hrkac G, Goncharov A, Allwood DA, Dean J. (2008) Micromagnetic calculation of spin wave propagation for magnetologic devices, Journal of Applied Physics, volume 103, no. 7, DOI:10.1063/1.2836791.
• Hrkac G, Schrefl T, Bance S, Allwood D, Goncharov A, Dean J, Suess D. (2008) Mutual phase locking in high-frequency microwave nano-oscillators as a function of field angle, Journal of Magnetism and Magnetic Materials, volume 320, no. 17, DOI:10.1016/j.jmmm.2008.03.046.
• Mistral Q, van Kampen M, Hrkac G, Kim J-V, Devolder T, Crozat P, Chappert C, Lagae L, Schrefl T. (2008) Current-driven vortex oscillations in metallic nanocontacts, Phys Rev Lett, volume 100, no. 25, DOI:10.1103/PhysRevLett.100.257201. [PDF]

2007

• Schrefl T, Hrkac G, Bance S, Suess D, Ertl O, Fidler J. (2007) Numerical Methods in Micromagnetics (Finite Element Method), Handbook of Magnetism and Advanced Magnetic Materials, Wiley, DOI:10.1002/9780470022184.hmm203.
• Mistral Q, van Kampen M, Hrkac G, Kim J-V, Devolder T, Crozat P, Chappert C, Lagae L, Schrefl T. (2007) Current-driven vortex oscillations in metallic nanocontacts, DOI:10.48550/arxiv.0710.5680.
• Hrkac G, Schrefl T, Bance S, Allwood D, Goncharov A, Dean J, Suess D. (2007) Mutual phase-locking in high frequency microwave nanooscillators as function of field angle, DOI:10.48550/arxiv.0711.1770.
• Hrkac G, Bance S, Goncharov A, Schrefl T, Suess D. (2007) Thermal stability of bubble domains in ferromagnetic discs, Journal of Physics D: Applied Physics, volume 40, no. 9, pages 2695-2698, DOI:10.1088/0022-3727/40/9/002.
• Suess D, Eder S, Lee J, Dittrich R, Fidler J, Harrell JW, Schrefl T, Hrkac G, Schabes M, Supper N. (2007) Reliability of Sharrocks equation for exchange spring bilayers, Physical Review B - Condensed Matter and Materials Physics, volume 75, no. 17, DOI:10.1103/PhysRevB.75.174430.
• Goncharov A, Schrefl T, Hrkac G, Dean J, Bance S, Suess D, Ertl O, Dorfbauer F, Fidler J. (2007) Recording simulations on graded media for area densities of up to 1 Tbit in.2, Applied Physics Letters, volume 91, no. 22, DOI:10.1063/1.2804609.

2006

• Hrkac G, Schrefl T, Schabes M. (2006) A combined vector and scalar potential method for 3D magnetic fields and transient Eddy current effects in recording head coils, PHYSICA B-CONDENSED MATTER, volume 384, no. 1-2, pages 253-255, DOI:10.1016/j.physb.2006.06.066. [PDF]
• Bance S, Schrefl T, Hrkac G, Allwood DA, Suess D, Brownlie C, McVitie S, Chapman JN. (2006) Transitions Between Vortex and Transverse Walls in NiFe Nano-Structures, IEEE Transactions on Magnetics, volume 42, no. 10, pages 2966-2968, DOI:10.1109/TMAG.2006.878393.
• Schrefl T, Suess D, Hrkac G, Kirschner M, Ertl O, Dittrich R, Fidler J. (2006) Nanomagnetic simulations, pages 91-118, DOI:10.1007/0-387-23316-4_4.
• Bance S, Hrkac G, Suess D, Brownlie C, McVitie S, Schrefl T. (2006) Transition from vortex to transverse walls in NiFe nano-structures, INTERMAG 2006 - IEEE International Magnetics Conference, DOI:10.1109/INTMAG.2006.374974.
• Kirschner M, Schrefl T, Hrkac G, Dorfbauer F, Suess D, Fidler J. (2006) Relaxation times and cell size in nonzero-temperature micromagnetics, Physica B: Condensed Matter, volume 372, no. 1-2, pages 277-281, DOI:10.1016/j.physb.2005.10.066.
• Fidler J, Schrefl T, Suess D, Ertl O, Kirschner M, Hrkac G. (2006) Full micromagnetics of recording on patterned media, Physica B: Condensed Matter, volume 372, no. 1-2, pages 312-315, DOI:10.1016/j.physb.2005.10.074.
• Hrkac G, Kirschner M, Dorfbauer F, Suess D, Ertl O, Fidler J, Schrefl T. (2006) Influence of eddy currents on the effective damping parameter, Journal of Applied Physics, volume 99, no. 8, DOI:10.1063/1.2168436.
• Ertl O, Hrkac G, Suess D, Kirschner M, Dorfbauer F, Fidler J, Schrefl T. (2006) Multiscale micromagnetic simulation of giant magnetoresistance read heads, Journal of Applied Physics, volume 99, no. 8, DOI:10.1063/1.2162812.
• Dorfbauer F, Schrefl T, Kirschner M, Hrkac G, Suess D, Ertl O, Fidler J. (2006) Nanostructure calculation of CoAg core-shell clusters, Journal of Applied Physics, volume 99, no. 8, DOI:10.1063/1.2176107.
• Allwood DA, Schrefl T, Hrkac G, Hughes IG, Adams CS. (2006) Mobile atom traps using magnetic nanowires, Applied Physics Letters, volume 89, no. 1, DOI:10.1063/1.2219397.
• Hrkac G, Schrefl T, Schabes M. (2006) A combined vector and scalar potential method for 3D magnetic fields and transient Eddy current effects in recording head coils, Physica B: Condensed Matter, volume 384, no. 1-2, pages 253-255, DOI:10.1016/j.physb.2006.06.066.

2005

• Schrefl T, Schabes ME, Suess D, Ertl O, Kirschner M, Dorfbauer F, Hrkac G, Fidler J. (2005) Partitioning of the perpendicular write field into head and SUL contributions, INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005, 2015 IEEE Magnetics Conference (INTERMAG), pages 491-492, DOI:10.1109/intmag.2005.1463674.
• Suess D, Schrefl T, Fähler S, Kirschner M, Hrkac G, Dorfbauer F, Fidler J. (2005) Exchange spring media for perpendicular recording, Applied Physics Letters, volume 87, no. 1, DOI:10.1063/1.1951053.
• Hrkac G, Schrefl T, Ertl O, Suess D, Kirschner M, Dorfbauer F, Fidler J. (2005) Influence of eddy current on magnetization processes in submicrometer permalloy structures, IEEE Transactions on Magnetics, volume 41, no. 10, pages 3097-3099, DOI:10.1109/TMAG.2005.855234.
• Suess D, Schrefl T, Kirschner M, Hrkac G, Dorfbauer F, Ertl O, Fidler J. (2005) Optimization of exchange spring perpendicular recording media, IEEE Transactions on Magnetics, volume 41, no. 10, pages 3166-3168, DOI:10.1109/TMAG.2005.855284.
• Dittrich R, Schrefl T, Kirschner M, Suess D, Hrkac G, Dorfbauer F, Ertl O, Fidler J. (2005) Thermally induced vortex nucleation in permalloy elements, IEEE Transactions on Magnetics, volume 41, no. 10, pages 3592-3594, DOI:10.1109/TMAG.2005.854736.
• Schrefl T, Schabes ME, Suess D, Ertl O, Kirschner M, Dorfbauer F, Hrkac G, Fidler J. (2005) Partitioning of the perpendicular write field into head and sul contributions, IEEE Transactions on Magnetics, volume 41, no. 10, pages 3064-3066, DOI:10.1109/TMAG.2005.855227.
• Hrkac G, Schrefl T, Ertl O, Kirschner M, Suess D, Fidler J. (2005) Influence of eddy current on magnetization processes in sub-micron permalloy structures, INTERMAG ASIA 2005: Digests of the IEEE International Magnetics Conference, DOI:10.1109/intmag.2005.1463844.
• Suess D, Schrefl T, Kirschner M, Hrkac G, Dorfbauer F, Fidler J. (2005) Optimization of exchange spring perpendicular recording media, INTERMAG ASIA 2005: Digests of the IEEE International Magnetics Conference, pages 1585-1586, DOI:10.1109/intmag.2005.1464226.
• Suess D, Schrefl T, Dittrich R, Kirschner M, Dorfbauer F, Hrkac G, Fidler J. (2005) Exchange spring recording media for areal densities up to 10 Tbit/in ², Journal of Magnetism and Magnetic Materials, volume 290-291 PART 1, pages 551-554, DOI:10.1016/j.jmmm.2004.11.525.
• Dorfbauer F, Schrefl T, Suess D, Kirschner M, Hrkac G, Fidler J. (2005) Pulsed inductive microwave magnetometer response calculated for IrMn/FeNi bilayers, European Physical Journal B, volume 45, no. 2, pages 267-271, DOI:10.1140/epjb/e2005-00179-2.
• Hrkac G, Kirschner M, Dorfbauer F, Suess D, Ertl O, Fidler J, Schrefl T. (2005) Three-dimensional micromagnetic finite element simulations including eddy currents, Journal of Applied Physics, volume 97, no. 10, DOI:10.1063/1.1852211.
• Kirschner M, Schrefl T, Dorfbauer F, Hrkac G, Suess D, Fidler J. (2005) Cell size corrections for nonzero-temperature micromagnetics, Journal of Applied Physics, volume 97, no. 10, DOI:10.1063/1.1846411.

2003

• Schrefl T, Hrkac G, Suess D, Scholz W, Fidler J. (2003) Coercivity and remanence in self-assembled FePt nanoparticle arrays, Journal of Applied Physics, volume 93, no. 10 2, pages 7041-7043, DOI:10.1063/1.1557398.

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