Argonne National Laboratory

Materials Science Division

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Axel Hoffmann

Principal Investigator

Materials Science Division; Bldg. 223
Argonne National Laboratory
9700 South Cass Ave.
Argonne, IL 60439

phone: 630-252-5469
fax: 630-252-9595
email: hoffmann@anl.gov


Biography

Axel Hoffmann received his Diploma degree with honors from the RWTH Aachen in 1994 and his Ph.D. in Physics from the University of California – San Diego in 1999. After receiving his doctorate he was a postdoctoral fellow at the Los Alamos National Laboratory working on neutron scattering from magnetic heterostructures. In 2001 he joined the Materials Science Division of the Argonne National Laboratory, where he is currently a staff member in the Magnetic Thin Film Group. His research interests encompass a wide variety of magnetism related subjects, including basic properties of magnetic heterostructures, spin-transport in novel geometries, and biomedical applications of magnetism. His main research focus has recently been on pure spin currents investigated by magnetotransport and magnetization dynamic measurements. He has more than 100 publications, four book chapters, and three magnetism-related U.S. patents. In the past he served as the chair for the Topical Group on Magnetism and its Applications of the American Physical Society and the chair of Technical Committee for the IEEE Magnetics Society. Currently he is an associate editor for the Journal of Applied Physics and a senior IEEE member. He has been active in many Intermag and Magnetism and Magnetic Materials Conferences, including serving as a publication co-chair for the 2007 Joint MMM/Intermag conference and a program co-chair of the MMM conference in 2010. For 2011 he has been designated a Distinguished Lecturer for the IEEE Magnetics Society and in 2013 he will be the general chair for the MMM Conference.

Publications

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Magnetic field enhancement of non-local spin signals in Ni80Fe20/Ag lateral spin valves

G. Mihajlovic, S. I. Erlingsson, K. Výborný, J. E. Pearson, S. D. Bader, and A. Hoffmann,

Physical Review B, submitted.

Role of anisotropy configuration in exchange-biased systems

E. Jiménez, J. Camarero, P. Perna, N. Mikuszeit, F. J. Teran, J. Sort, J. Nogués, J. M. García-Martín, A. Hoffmann, B. Dieny, and R. Miranda

Journal for Applied Physics, submitted.

Detection and quantification of inverse spin Hall effect from spin pumping in permalloy/normal metal bilayers

O. Mosendz, V. Vlaminck, J. E. Pearson, F. Y. Fradin, G. E. W. Bauer, S. D. Bader, and A. Hoffmann,

Physical Review B 82, 214403 (2010).

Enhanced spin signals due to native oxide formation in Ni80Fe20/Ag lateral spin valves

G. Mihajlovic, D. K. Schreiber, Y. Liu, J. E. Pearson, S. D. Bader, A. K. Petford-Long, and A. Hoffmann,

Applied Physics Letters 97, 112501 (2010).

Magnetic memory based on La0.7Ca0.3MnO3/YBa2Cu3O7/La0.7Ca0.3MnO3 ferromagnet/superconductor hybrid structures

N. M. Nemes, C. Visani, C. Leon, M. Garcia-Hernandez, F. Simon, T. Fehér, S. G. E. te Velthuis, A. Hoffmann, and J. Santamaria,

Applied Physics Letters 97, 032501 (2010).

Surface Spin Flip Probability of Mesoscopic Ag Wires

G. Mihajlovic, J. E. Pearson, S. D. Bader, and A. Hoffmann,

Physical Review Letters 104, 237202 (2010).

Broadband Mag-Noise of Patterned Permalloy Thin Films

H. Zhang, C. Li, R. Divan, A. Hoffmann, and P. Wang,

IEEE Transactions on Magnetics 46, 2442 (2010).

Temperature dependent nucleation and annihilation of individual magnetic vortices

G. Mihajlovic, M. S. Patrick, J. E. Pearson, V. Novosad, S. D. Bader, M. Field, G. J. Sullivan, and A. Hoffmann,

Applied Physics Letters 96, 112501 (2010).

Directionally controlled superconductivity in ferromagnet/superconductor/ferromagnet trilayers with biaxial easy axes

C. Visani, N. M. Nemes, M. Rocci, Z. Sefrioui, C. Leon, S. G. E. te Velthuis, A. Hoffmann, M. R. Fitzsimmons, F. Simon, T. Feher, M. Garcia-Hernandez, and J. Santamaria,

Physical Review B 81, 094512 (2010).

Quantifying Spin Hall Angles from Spin Pumping: Experiment and Theory

O. Mosendz, J. E. Pearson, F. Y. Fradin, G. E. W. Bauer, S. D. Bader, and A. Hoffmann,

Physical Review Letters 104, 046601 (2010).

Erratum: “Translational-mode dynamics of exchange-biased vortices” [J. Appl. Phys. 103, 07B102 (2008)]

K. S. Buchanan, A. Hoffmann, V. Novosad, and S. D. Bader

Journal of Applied Physics 107, 029902 (2010).

Supression of spin-pumping by a MgO tunnel-barrier

O. Mosendz, J. E. Pearson, F. Y. Fradin, S. D. Bader, and A. Hoffmann,

Applied Physics Letters 96, 022502 (2010).

Pure Spin Currents

A. Hoffmann,

In: Yearbook of Science & Technology 2010 (McGraw-Hill, New York, 2009).

Direct-current effects on magnetization reversal properties of submicron-size Permalloy patterns for radio-frequency devices

H. Zhang, A. Hoffmann, R. Divan, and P. Wang,

Applied Physical Letters 95, 232502 (2009).

DC Current Effects on High-Frequency Properties of Patterned Permalloy Thin Films

H. Zhang, A. Hoffmann, R. Divan, and P. Wang,

IEEE Transactions on Magnetics 49, 5296 (2009).

Micro-Hall position sensing of magnetic nanowires

G. Mihajlovic, A. Hoffmann, and S. von Molnár

Journal of Applied Physics 106, 074518 (2009).

Negative Nonlocal Resistance in Mesoscopic Gold Hall Bars: Absence of the Giant Spin Hall Effect

G. Mihajlovic, J. E. Pearson, M. A. Garcia, S. D. Bader, and A. Hoffmann,

Physical Review Letters 103, 166601 (2009).

Imaging of lateral spin valves with soft x-ray microscopy

O. Mosendz, G. Mihajlovic, J. E. Pearson, P. Fischer, M.-Y. Im, S. D. Bader, and A. Hoffmann,

Physical Review B 80, 104439 (2009).

Highly asymmetric magnetic behavior in exchange biased systems induced by noncollinear field cooling

E. Jiménez, J. Camarero, J. Sort, J. Nogués, A. Hoffmann, F. J. Teran, P. Perna, J. M. García-Martín, B. Dieny, and R. Miranda

Applied Physics Letters 95, 122508 (2009).

Patterned Permalloy Films for High Frequency on Chip Circuit Components

S. Azeemuddin, R. Divan, A. Hoffman, and P. Wang,

European Journal of Scientific Research 32, 141 (2009).

X-ray Magnetic Circular Dichroism and Small Angle Neutron Scattering Study of Thiol Capped Gold Nanoparticles

J. de la Venta, V. Bouzas, A. Pucci, M. A. Laguna-Marco, D. Haskel, S. G. E. te Velthuis, A. Hoffmann, J. Lal, M. Bleuel, G. Ruggeri, C. de Julián Fernández, and M. A. García,

Journal of Nanoscience and Nanotechnology 9, 6439 (2009).

Magnetic depth profile of a modulation doped La1-xCaxMnO3 exchange-based system

A. Hoffmann, S. J. May, S. G. E. te Velthuis, S. Park, M. R. Fitzsimmons, G. Campillo, and M. E. Gómez,

Physical Review B 80, 052403 (2009).

Emergence of noncollinear anisotropies from interfacial magnetic frustration in exchange-bias systems

E. Jiménez, J. Camarero, J. Sort, J. Nogués, N. Mikuszeit, J. M. García-Martín, A. Hoffmann, B. Dieny, and R. Miranda,

Physical Review B 80, 014415 (2009).

Tailoring High-Frequency Properties of Permalloy Films via Submicron Patterning

P. Wang, H. Zhang, R. Divan, and A. Hoffmann,

IEEE Transactions on Magnetics 45, 71 (2009).

High-Frequency Properties of Permalloy Nanowire Arrays for RF Devices

H. Zhang, C. Song, R. Divan, A. Hoffmann, and P. Wang,

In: IEEE-NANO 2008, Proceedings of the 8th IEEE Conference on Nanotechnology, Arlington, Texas, USA, 621-624 (2008).

Physical properties in thin films of iron oxides

J. D. Uribe, J. Osorio, C. A. Barrero, D. Giratá, A. L. Morales, and A. Hoffmann,

Miroelectronics Journal 39, 1391 (2008).

Origin of the inverse spin-switch behavior in manganite/cuprate/manganite trilayers

N. M. Nemes, M. García-Hernández, S. G. E. te Velthuis, A. Hoffmann, C. Visani, J. Garcia-Barriocanal, V. Peña, D. Arias, Z. Sefrioui, C. Leon, and J. Santamaría,

Physical Review B 78, 094515 (2008).

Efectos del Dopaje 57Fe en las Propiedades Estructurales y Magnéticas de Películas Delgadas de Manganitas La1/3Ca1/3Mn1-yFeyO3 (y=0, 0.01 y 0.03)

O. Arnarche, A. Hoffmann, and D. Giratá,

Revista Colombiana de Física 40, 295 (2008).

Superconducting vortex pinning with artificial magnetic nanostructures

M. Vélez, J. I. Martín, J. E. Villegas, A. Hoffmann, E. M. González, J. L. Vicent, and I. K. Schuller

Journal of Magnetism and Magnetic Materials 320, 2547 (2008).

Fe-Doping and Strain Effects on Structural and Magnetotransport Properties of La2/3Ca1/3Mn1-yFeyO3 Thin Films

O. Arnache, D. Giratá, and A. Hoffmann,

Physical Review B 77, 214430 (2008).

Exchange-Biased Magnetic Vortices

A. Hoffmann, J. Sort, K. S. Buchanan, and J. Nogués,

IEEE Transactions on Magnetics 44, 1968 (2008).

Síntesis y Caracterizacíon Estructural y Magnética de Manganitas La2/3Ca1/3MnO3 dopadas con 57Fe

O. Arnarche, A. Hoffmann, and D. Giratá,

Revista Colombiana de Física 40, 123 (2008).

Reflectividad DRX y Propiedades Magnéticas de Películas Delgadas de Hematita a – Fe2O3

J. D. Uribe, J. Osorio, O. Arnarche, D. Giratá, and A. Hoffmann,

Revista Colombiana de Física 40, 120 (2008).

Dependencia de Propiedades Magnéticas con Espesores en Bicapas Ferro-La2/3Ca1/3MnO3/Antiferro-La1/3Ca2/3MnO3 en Campo Aplicado Cero

L. Marin, M. E. Gomez, J.-G. Ramirez, and A. Hoffmann,

Revista Colombiana de Física 40, 17 (2008).

Effect of Fe Doping on Structural and Magnetic Properties of La2/3Ca1/3Mn1-yFeyO3 (y = 0–0.03) Thin Films

O. Arnache, A. Hoffmann, and D. Giratá,

Microelectronics Journal 39, 544 (2008).

Tailoring the magnetization reversal of elliptical dots using exchange bias (invited)

J. Sort, K. S. Buchanan, J. E. Pearson, A. Hoffmann, E. Menéndez, G. Salazar-Alvarez, M. D. Baró, B. Rodmacq, B. Dieny, and J. Nogués,

Journal of Applied Physics 103, 07C109 (2008).

Enhanced Pinning of Superconducting Vortices by Magnetic Vortices

A. Hoffmann, L. Fumagalli, N. Jahedi, J. C. Sautner, J. E. Pearson, G. Mihajlovic, and V. Metlushko,

Physical Review B 77, 060506(R) (2008).

Translational-mode dynamics of exchange-biased vortices

K. S. Buchanan, A. Hoffmann, V. Novosad, and S. D. Bader,

Journal of Applied Physics 103, 07B102 (2008).

Magneto-optic measurement of Brownian relaxation of magnetic nanoparticles

S.-H. Chung, M. Grimsditch, A. Hoffmann, S. D. Bader, J. Xie, S. Peng, and S. Sun,

Journal of Magnetism and Magnetic Materials 320, 91 (2008).

Magnetic and Structural Studies of Magnetite Thin Films

J. D. Uribe, J. Osorio, D. Giratá, A. Morales, J. Pearson, and A. Hoffmann,

Revista Colombiana de Física 39, 593 (2007).

Pure Spin-Currents

A. Hoffmann,

Physica Status Solidi C 4, 4236 (2007).

Detailed magnetic and structural properties of exchange-biased La1-xCaxMnO3

M. E. Gómez, G. Campillo, J.-G. Ramirez, A. Hoffmann, and J. Guimpel,

Physica Status Solidi C 4, 4181 (2007).

Aproximación al efecto exchange bias en bicapas de La2/3Ca1/3MnO3/La1/3Ca2/3MnO3

L. Marin, J. G. Ramírez, M. E. Gómez, A. Hoffmann, C. Quinayas, and G. Bolaños,

Revista Colombiana de Física 39, 51 (2007).

Magnetoresistance in La0.7Ca0.3MnO3–YBa2Cu3O7 F/S/F trilayers

V. Peña, C. Visani, F. Bruno, J. Garcia-Barriocanal, D. Arias, A. Rivera, Z. Sefrioui, C. Leon, S. G. E. Te Velthuis, A. Hoffmann, N. Nemes, M. Garcia-Hernandez, J. L. Martinez, and J. Santamaria,

Journal of Magnetism and Magnetic Materials 316, e745 (2007).

Hybrid Nanomaterials from Hierarchical Self-Assembly of Nanoparticles and Clusters on Diblock Copolymer Films

S. B. Darling, A. Hoffmann, N. A. Yufa, S. D. Bader, and S. J. Sibener,

Polymeric Materials: Science and Engineering 96, 31 (2007).

Spin dependent transport at oxide La0.7Ca0.3MnO3/YBa2Cu3O7 ferromagnet/superconductor interfaces

V. Peña, N. Nemes, C. Visani, F. Y. Bruno, D. Arias, Z. Sefrioui, C. Leon, S. G. E. te Velthuis, A. Hoffmann, M. Garcia-Hernandez, J. L. Martinez, and J. Santamaría,

Journal of the European Ceramic Society 27, 3967 (2007).

Domain States determined by Neutron Refraction and Scattering

A. Hoffmann and G. P. Felcher,

In: The Handbook of Magnetism and Advanced Magnetic Materials, Volume 3, edited by Helmut Kronmüller and Stuart Parkin, (Wiley, New York, 2007) p. 1211.

Brownian Motion in Biological Sensing

A. Hoffmann, S.-H. Chung, S. D. Bader, L. Makowski, and L. Chen,

in: Biomedical Applications of Nanotechnology, edited by V. Labhasetwar and D. L. Leslie-Pelicki, (Wiley, New York, 2007) p. 83–103.

Tuning metal surface diffusion on diblock copolymer films

S. B. Darling and A. Hoffmann,

Journal of Vacuum Science and Technology A 25, 1048 (2007).

Issues in Nanomagnetism

S. D. Bader, K. S. Buchanan, S.-H. Chung, K. Y. Guslienko, A. Hoffmann, Y. Ji, and V. Novosad,

Superlattices and Microstructure 41, 72 (2007).

Tenth Joint MMM-Intermag Conference 2007 IEEE Publication Chair’s Preface

A. Hoffmann,

IEEE Transactions on Magnetics 43, 2083 (2007).

Vortex magnetization reversal in double-layer ferromagnetic/antiferromagnetic dots

K. Y. Guslienko and A. Hoffmann,

Journal of Applied Physics 101, 093901 (2007).

Magnetic Instability Regions in Patterned Structures: Influence of Element Shape on Magnetization Reversal Dynamics

X. F. Han, M. Grimsditch, J. Meersschaut, A. Hoffmann, Y. Ji, J. Sort, J. Nogués, R. Divan, J. E. Pearson, and D. J. Keavney,

Physical Review Letters 98, 147202 (2007).

Non-local spin injection in lateral spin valves

Y. Ji, A. Hoffmann, J. S. Jiang, J. E. Pearson, and S. D. Bader,

Journal of Physics D: Applied Physics 40, 1280 (2007).

Publisher’s Note: Spin-dependent magnetoresistance of ferromagnet/superconductor/ferromagnet La0.7Ca0.3MnO3 / YBa2Cu3O7-d / La0.7Ca0.3MnO3 trilayers

C. Visani, V. Peña, J. Garcia-Barriocanal, D. Arias, Z. Sefrioui, J. Santamaria, N. M. Nemes, M. Garcia-Hernandez, J. L. Martinez, S. G. E. te Velthuis, and A. Hoffmann,

Physical Review B 75, 059904(E) (2007).

Spin-dependent magnetoresistance of ferromagnet/superconductor/ferromagnet La0.7Ca0.3MnO3 / YBa2Cu3O7-d / La0.7Ca0.3MnO3 trilayers

C. Visani, V. Peña, J. Garcia-Barriocanal, D. Arias, Z. Sefrioui, J. Santamaria, N. M. Nemes, M. Garcia-Hernandez, J. L. Martinez, S. G. E. te Velthuis, and A. Hoffmann,

Physical Review B 75, 054501 (2007).

Substrate-free Biosensing using Brownian Rotation of Bio-conjugated Magnetic Nanoparticles

S.-H. Chung, A. Hoffmann, L. Chen, S. Sun, K. Guslienko, M. Grimsditch, and S. D. Bader,

Journal of Magnetics (Korean Magnetic Society) 11, 189 (2006).

Large magnetoresistance at oxide La0.7Ca0.3MnO3 and YBa2Cu3O7 interfaces

V. Peña, N. Nemes, J. Garcia-Barriocanal, Z. Sefrioui, C. Leon, S. G. E. te Velthuis, A. Hoffmann, M. Garcia-Hernandez, J. L. Martinez, and J. Santamaría,

Advances in Science and Technology 45, 2545 (2006).


Permalloy thin films exchange coupled to arrays of cobalt islands

A. Fraile Rodríguez, L. J. Heyderman, F. Nolting, A. Hoffmann, J. E. Pearson, L. M. Doeswijk, M. A. F. van den Boogaart, and J. Brugger,

Applied Physics Letters 89, 142508 (2006).

Magnetotransport Properties in Epitaxial Exchange-Biased La2/3Ca1/3MnO3/La1/3Ca2/3MnO3 Superlattices

M. E. Gomez, G. Campillo, J.-G. Ramírez, P. Prieto, A. Hoffmann, J. Guimpel, N. Haberkorn, A. Condó, and F. Lovey,

IEEE Transactions on Magnetism 42, 2981 (2006).

Advances in nanomagnetism via X-ray techniques

G. Srajer, L. H. Lewis, S. D. Bader, A. J. Epstein, C. S. Fadley, E. E. Fullerton, A. Hoffmann, J. B. Kortright, K. M. Krishnan, S. A. Majetich, T. S. Rahman, C. A. Ross, M. B. Salamon, I. K. Schuller, T. C. Schulthess, and J. Z. Sun,

Journal of Magnetism and Magnetic Materials 307, 1 (2006).

Comment on “Photoemission Study of YBa2Cu3Oy Thin Films under Light Illumination”

A. Hoffmann, G. Nieva, J. Guimpel, Y. Bruynseraede, J. Santamaría, D. Lederman, and I. K. Schuller,

Physical Review Letters 97, 119701 (2006).

Field Evolution of Tilted Vortex Cores in Exchange-Biased Ferromagnetic Dots

K. Yu. Guslienko and A. Hoffmann,

Physical Review Letters 97, 107203 (2006).

Imprinting Vortices into Antiferromagnets

J. Sort, K. S. Buchanan, V. Novosad, A. Hoffmann, G. Salazar-Alvarez, A. Bollero, M. D. Baró, B. Dieny, and J. Nogués,

Physical Review Letters 97, 067201 (2006).

Microwave Dielectric Properties of On-Chip Liquid Films

C. Song, S. Azimuudin, B. Lee, F. Harackiewicz, M. Yen, D. Ralu, A. Hoffman, and P. Wang,

In: Proceedings of Life Science Systems and Applications Workshop, 2006 (IEEE/NLM 2006), P. 1–2.

Large magnetoresistance in oxide based ferromagnet / superconductor spin switches

V. Peña, N. Nemes, C. Visani, J. Garcia-Barriocanal, F. Bruno, D. Arias, Z. Sefrioui, C. Leon, S. G. E. te Velthuis, A. Hoffmann, M. Garcia-Hernandez, and J. Santamaría,

In: Degradation Processes in Nanostructured Materials, edited by Mircea Chipara, Orazio Puglisi, Ralph Skomski, Frank R. Jones, and Benjamin S. Hsiao (Materials Research Society Symposium Proceedings, Vol. 887, Warrendale, PA, 2006), p. Q11-02.1–Q11-02.8.

High-Frequency Domain-Wall Motion and Magnetization Rotation of Patterned Permalloy Films under External Magnetic Field Excitation

S. Azeemuddin, A. Hoffmann, R. Divan, M. J. Donahue, S. H. Chung, and P. Wang,

In: IEEE-NANO 2006, Proceedings of the 6th IEEE Conference on Nanotechnology, Cincinatti, Ohio, USA, 853-856 (2006).

Influence of ferromagnetic thickness on structural and magnetic properties of exchange-biased manganite superlattices

G. Campillo, M. E. Gomez, A. Berger, A. Hoffmann, R. Escudero, and P. Prieto,

Journal of Applied Physics 99, 08C106 (2006).

Frustrated magnetic vortices in a triad of permalloy rings: Magneto-optical Kerr effect, magnetic force microscopy, and micromagnetic simulations

V. Rose, K. Buchanan, S.-H. Chung, M. Grimsditch, V. Metlushko, A. Hoffmann, V. Novosad, S. D. Bader, and H. Ibach,

Physical Review B 73 094442 (2006).

Magnetic viruses via nano-capsid templates

C. Liu, S.-H. Chung, Q. Jin, A. Sutton, F. Yan, A. Hoffmann, B. K. Kay, S. D. Bader, L. Makowksi, and L. Chen,

Journal of Magnetism and Magnetic Materials 302, 47 (2006).

Dynamics of thin-film spin-flip transistors with perpendicular source-drain magnetizations

X. Wang, G. E. W. Bauer, and A. Hoffmann,

Physical Review B 73, 054436 (2006).

Enhanced spin injection polarization in Co/Cu/Co nonlocal lateral spin valves

Y. Ji, A. Hoffmann, J. E. Pearson, and S. D. Bader,

Applied Physical Letters 88, 052509 (2006).

Coherent Inelastic Light Scattering from a Microwave-Excited Array of Magnetic Particles

M. Grimsditch, F. Y. Fradin, Y. Ji, A. Hoffmann, R. E. Camley, V. Metlushko, and V. Novosad,

Physical Review Letters 96, 047401 (2006).

Controlling magnetic vortices through exchange bias

J. Sort, G. Salazar-Alvarez, M. D. Baró, B. Dieny, A. Hoffmann, V. Novosad, and J. Nogués,

Applied Physics Letters 88, 042502 (2006).

Suppressed magnetization in La0.7Ca0.3MnO3/YBa2Cu3O7-d superlattices

A. Hoffmann, S. G. E. te Velthuis, Z. Sefrioui, J. Santamaría, M. R. Fitzsimmons, S. Park, and M. Varela,

Physical Review B 72, 140407(R) (2005).

Erratum: Symmetry Driven Irreversibilities at Ferromagnetic-Antiferromagnetic Interfaces [Phys. Rev. Lett. 93, 097203 (2004)]

A. Hoffmann

Physical Review Letters 95, 159901 (2005).

Magnetization Reversal in Submicron Disks: Exchange Biased Vortices

J. Sort, A. Hoffmann, S.-H. Chung, K. Buchanan, M. Grimsditch, M. D. Baró, B. Dieny, and J. Nogués,

Physical Review Letters 95, 067201 (2005).

Origin of the Asymmetric Magnetization Reversal Behavior in Exchange-Biased Systems: Competing Anisotropies

J. Camarero, J. Sort, A. Hoffmann, J. M. Garcia-Martín, B. Dieny, R. Miranda, and J. Nogués,

Physical Review Letters 95, 057204 (2005).

Antiferromagnetic Thickness Dependence of Exchange Bias in La-Ca-Mn-O Ferromagnetic/Antiferromagnetic Superlattices

G. Campillo, A. Hoffmann, M. E. Gómez, and P. Prieto,

Revista Colombiana de Física 37, 215 (2005).

Interplay between exchange bias and uniaxial anisotropy in a ferromagnetic/antiferromagnetic exchange-coupled system

S. H. Chung, A. Hoffmann, and M. Grimsditch,

Physical Review B 71, 214430 (2005).


Biological sensing with magnetic nanoparticles using Brownian relaxation (invited)

S.-H. Chung, A. Hoffmann, K. Guslienko, S. D. Bader, C. Liu, B. Kay, L. Makowski, and L. Chen,

Journal of Applied Physics 97, 10R101 (2005).

Exchange bias and magnetic structure in modulation-doped manganite superlattices

G. Campillo, A. Hoffmann, M. E. Gomez, and P. Prieto,

Journal of Applied Physics 97, 10K104 (2005).

Giant Magnetoresistance in Ferromagnet / Superconductors Superlattices

V. Peña, Z. Sefroui, D. Arias, C. Leon, J. Santamaria, J. L. Martinez, S. G. E. te Velthuis, and A. Hoffmann,

Physical Review Letters 94 057002 (2005).

Magnetic Viruses for Biological and Medical Applications

A. Hoffmann,

Magnetics Business & Technology, Spring, 24 (2005).

Spin Injection, Diffusion, and Detction in Lateral Spin-Valves

Y. Ji, A. Hoffmann, J. S. Jiang, and S. D. Bader,

Applied Physics Letters 85, 6218 (2004).

Biological sensors based on Brownian relaxation of magnetic nanoparticles

S. H. Chung, A. Hoffmann, S. D. Bader, C. Liu, B. Kay, L. Makowski, and L. Chen,

Applied Physics Letters 85, 2971 (2004).

Symmetry driven irreversibilities at ferromagnetic-antiferromagnetic interfaces

A. Hoffmann,

Physical Review Letters 93, 097203 (2004).

Annealing-Dependent Magnetic Depth Profile in Ga1-xMnxAs

B. J. Kirby, J. A. Borchers, J. J. Rhyne, S. G. E. te Velthuis, A. Hoffmann, K. V. O’Donovan, T. Wojtowicz, X. Liu, W. L. Lim, and J. K. Furdyna,

Physical Review B 69, 081307 (2004).

Neutron Scattering Studies of Nanomagnetism and Artificially Structured Materials

M. R. Fitzsimmons, S. D. Bader, J. A. Borchers, G. P. Felcher, J. K. Furdyna, A. Hoffmann, J. B. Kortright, I. K. Schuller, T. C. Schulthess, S. K. Sinha, M. F. Toney, D. Weller, and S. Wolf,

Journal of Magnetism and Magnetic Materials 271, 103 (2004).

Tailoring the exchange bias in ferromagnetic/antiferromagnetic exchange-coupled systems via shape anisotropy

A. Hoffmann, M. Grimsditch, J. E. Pearson, J. Nogués, W. A. A. Macedo, and Ivan K. Schuller,

Physical Review B 67, 220406(R) (2003).

Exchange-induced anisotropies at ferromagnetic-antiferromagnetic interfaces above and below the Néel temperature

M. Grimsditch, A. Hoffmann, P. Vavassori, Hongtao Shi, and D. Lederman,

Physical Review Letters 90, 257201 (2003).

Isothermal tuning of exchange bias using pulsed fields

J. Nogués, J. Sort, S. Suriñach, J. S. Muñoz, M. D. Baró, J. F. Bobo, U. Lüders, E. Haanappel, M. R. Fitzsimmons, A. Hoffmann, and J. W. Cai,

Applied Physics Letters 82, 3044 (2003).

Induced Magnetic Moments at a Ferromagnet-Antiferromagnet Interface

A. Hoffmann, J. W. Seo, M. R. Fitzsimmons, H. Siegwart, J. Fompeyrine, J.-P. Locquet, J A. Dura, and C. F. Majkrzak,

Physical Review B 66, 220406(R) (2002).

Nanostructures and the Proximity Effect

M. I. Montero, Kai Liu, O. M. Stoll, A. Hoffmann, Ivan K. Schuller, Johan J. Åkerman, J. I. Martín, J. L. Vicent, S. M. Baker, T. P. Russell, C. Leighton, and J. Nogués,

Journal of Physics D: Applied Physics 35, 2398 (2002).

Influence of in-plane crystalline quality of an antiferromagnet on perpendicular exchange coupling and exchange bias

M.R. Fitzsimmons, C. Leighton, J. Nogués, A. Hoffmann, Kai Liu, C.F. Majkrzak, J.A. Dura, J.R. Groves, R.W. Springer, P.N. Arendt, V. Leiner, H. Lauter, and Ivan K. Schuller,

Physical Review B 65, 134436 (2002).

Interplay between the vortex lattice and arrays of submicrometric pinning centers

J.I. Martín, M. Vélez, E.M. González, A. Hoffmann, D. Jaque, M.I. Montero, E. Navarro, J.E. Villegas, Ivan K. Schuller, and J.L. Vicent

Physica C 369, 135 (2002).

Thickness dependent coercive mechanisms in exchange biased bilayers

C. Leighton, M.R. Fitzsimmons, A. Hoffmann, J. Dura, C.F. Majkrzak, M.S. Lund, and Ivan K. Schuller

Physical Review B 65, 064403 (2002).

Investigating magnetic proximity effects in NiO/Pd with polarized neutron reflectometry

A. Hoffmann, M.R. Fitzsimmons, J.A. Dura, and C.F. Majkrzak,

Physical Review B 65, 024428 (2002).

Influence of interfacial disorder and temperature on magnetization reversal in exchange-coupled bilayers

M.R. Fitzsimmons, C. Leighton, A. Hoffmann, P.C. Yashar, J. Nogués, C.F. Majkrzak, J.A. Dura, H. Fritzsche, and Ivan K. Schuller,

Physical Review B 64, 104415 (2001).

Deposition of epitaxial a-Fe2O3 layers for exchange bias studies by reactive d.c. magnetron sputtering

C. Leighton, A. Hoffmann, M.R. Fitzsimmons, J. Nogués, and Ivan K. Schuller,

Philosophical Magazine B 81, 1927 (2001).

Individual and Multi Vortex Pinning in Systems with Periodic Pinning Arrays

C. Reichhardt, G.T. Zimanyi, R.T. Scalettar, A. Hoffmann, and Ivan K. Schuller,

Physical Review B 64, 052503 (2001).

Two stage magnetization reversals in exchange biased bilayers

C. Leighton, M.R. Fitzsimmons, P. Yashar, A. Hoffmann, J. Nogués, J. Dura, C.F. Majkrzak, and Ivan K. Schuller,

Physical Review Letters 86, 4394 (2001).

Temperature dependence and mechanisms of vortex pinning by periodic arrays of Ni dots in Nb films

J.I. Martín, M. Vélez, A. Hoffmann, Ivan K. Schuller, and J.L. Vicent,

Physical Review B, 62, 9110 (2000).

Periodic Vortex Pinning with Magnetic and Non-Magnetic Dots: The Influence of Size

A. Hoffmann, P. Prieto, and Ivan K. Schuller,

Physical Review B, 61, 6958 (2000).

Photodoping Effects in High Critical Temperature Superconducting Films and Josephson Junctions

A. Gilabert, A. Hoffmann, M.G. Medici, and Ivan K. Schuller,

Journal of Superconductivity, 13, 1 (2000).

Artificially induced reconfiguration of the vortex lattice by arrays of magnetic dots

J.I. Martín, M. Vélez, A. Hoffmann, Ivan K. Schuller, and J.L. Vicent,

Physical Review Letters, 83, 1022 (1999).

Persistent photoconductivity in high-Tc superconductors

A. Hoffmann, Ivan K. Schuller, Z.F. Ren, J.Y. Lao, J.H. Wang, D. Girata, W. Lopera, and P. Prieto,

in: Application of Spectroscopy to Superconducting Materials, ACS Symposium Series, Vol. 720, edited by E. Faulques, (ACS Publications, Washington D.C., 1999), p. 216-229.

Photodoping of YBaCuO Grain Boundary Josephson Junctions

A. Gilabert, M.G. Medici, A. Hoffmann, I.K. Schuller, F. Schmidl, and P. Seidel,

Journal of Superconductivity, 12, 121 (1999).

Fabrication of submicrometric magnetic structures by electron beam lithography

J.I. Martín, Y. Jaccard, A. Hoffmann, J. Nogués, J.M. George, J.L. Vicent, and Ivan K. Schuller,

Journal of Applied Physics, 84, 411 (1998).

Effect of photodoping on the Fiske resonances of YBaCuO grain boundary Josephson junctions

M.G. Medici, J. Elly, M. Razany, A. Gilabert, F. Schmidl, P. Seidel, A. Hoffmann, and Ivan K. Schuller,

Journal of Superconductivity, 11, 225 (1998).

Pinning effects by arrays of magnetic dots on Niobium films

J.I. Martín, M. Vélez, J. Nogués, A. Hoffmann, Y. Jaccard, and Ivan K. Schuller,

Journal of Magnetism and Magnetic Materials, 177-181, 915 (1998).

Persistent Photoconductivity in overdoped High Tc thin films

A. Hoffmann, Ivan K. Schuller, Z.F. Ren, J.Y. Lao, and J.H. Wang,

Physical Review B, 56, 13742 (1997).

Effect of Light Irradiation on Fiske Resonances and Josephson Effect in High Tc Junctions

J. Elly, M.G. Medici, A. Gilabert, F. Schmidl, P. Seidel, A. Hoffmann, and Ivan K. Schuller,

Physical Review B, 56, R8507 (1997).

Persistent Photoconductivity in High Tc Grain Boundary Josephson Junctions

A. Hoffmann, Ivan K. Schuller, A. Gilabert, M.G. Medici, F. Schmidl, and P. Seidel,

Applied Physics Letters, 70, 2461 (1997).

Persistent Photoinduced Effects in High Tc Superconductors

A. Hoffmann, D. Reznik, and Ivan K. Schuller,

Advanced Materials, 9, 271 (1997).

Photoinduced enhancement of the Josephson effect in YBaCuO grain boundary junctions

A. Gilabert, A. Hoffmann, J. Elly, M.G. Medici, F. Schmidl, P. Seidel, and Ivan K. Schuller,

Journal of Low Temperature Physics, 106, 255 (1997).

Persistent Photoinduced Superconductivity

A. Hoffmann, J. Hasen, D. Lederman, T. Endo, Y. Bruynseraede, and Ivan K. Schuller,

Journal of Alloys and Compounds, 251, 87 (1997).

Search for new Superconductors in the Y-Ni-B-C System

B. Knigge, A. Hoffmann, D. Lederman, D.C. Vier, S. Schultz, and Ivan K. Schuller,

Journal of Applied Physics, 81, 2291 (1997).

Persistent Photoconductivity Spectrum of GdBa2Cu3O6.3 from the IR to UV Region

T. Endo, J. Santamaria, A. Hoffmann, and Ivan K. Schuller,

Czechoslovak Journal of Physics 46, 1123 Suppl. 2 (1996).

Enhancement of Persistent Photoconductivity by UV excitation in GdBa2Cu3O6.3

T. Endo, A. Hoffmann, J. Santamaria, and Ivan K. Schuller,

Physical Review B, 54, R3750 (1996).

Electronic Raman scattering of Tl-2201 and Tl-2223 and the symmetry of the energy gap

L.V. Gasparov, P. Lemmens, M. Brinkmann, A. Hoffmann, N.N. Kolesnikov, H. Thomas, K. Winzer, and G. Güntherodt,

Physica B 223 & 224, 484 (1996).

The pairing Mechanism in HTSC investigated by electronic Raman scattering

A. Hoffmann, P. Lemmens, L. Winkeler, and G. Güntherodt,

Journal of Low Temperature Physics 99, 201 (1995).

Raman Scattering of Extra Vibrational Modes in Mixed-Valence Compounds

P. Lemmens, A. Hoffmann, A.S. Mishchenko, M.Yu. Talantov, and G. Güntherodt,

Physica B 206 & 207, 371 (1995).

Electronic Raman Scattering of Tl-2223 and the Symmetry of the Superconducting Gap

A. Hoffmann, P. Lemmens, G. Güntherodt, V. Thomas, and K. Winzer,

Physica C 235-240, 1897 (1994).

Investigation of the out-of-plane transport in Bi2212 and Tm123 single crystals

L. Winkeler, P. Lemmens, A. Hoffmann, G. Güntherodt, V.I. Voronovka, and V.K. Yanovskii,

In: Applied Superconductivity, edited by H. C. Freyhardt, (DGM, Oberursel, 1994), p. 125.

 


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