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Search Publications by: Brian Kirby (Fed)

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Displaying 1 - 25 of 87

Room-temperature valence transition in a strain-tuned perovskite oxide

December 15, 2022
Vipul Chaturvedi, Supriya Ghosh, Dominique Gautreau, William M. Postiglione, John E. Dewey, Patrick Quarterman, Purnima P. Balakrishnan, Brian Kirby, Hua Zhou, Huikui Cheng, Amanda Huon, Timothy Charlton, Michael R. Fitzsimmons, Caroline Korostynski, Andrew Jacobson, Lucca Figari, Javier Garcia Barriocanal, T. Birol, K. A. Mkhoyan, Chris Leighton
Cobalt oxides have long been understood to display intriguing phenomena known as spin-state crossovers, where the cobalt ion spin changes vs. temperature, pressure, etc. A very different situation was recently uncovered in praseodymium-containing cobalt

Chiral Spin Bobbers in Exchange-Coupled Hard-Soft Magnetic Bilayers

November 17, 2021
X. H. Zhang, T. R. Gao, L. Fang, S. Fackler, Julie Borchers, Brian Kirby, Brian B. Maranville, S. E. Lofland, A. T. N'Diaye, E. Arenholz, A. Ullah, J. Cui, R. Skomski, Ichiro Takeuchi
The spin structure of exchange-coupled MnBi:Co-Fe bilayers is investigated by X-ray magnetic circular dichroism (XMCD), polarized neutron reflectometry (PNR), and micromagnetic simu-lations. The purpose of the present research is two-fold. First, the

Electrically Driven Exchange Bias via Solid State Magneto-Ionics

August 4, 2021
Peyton Murray, Christopher Jensen, Alberto Quintana, Junwei Zhang, Xixiang Zhang, Alexander Grutter, Brian Kirby, Kai Liu
Electrically induced ionic motion offers a new way to realize voltage-controlled magnetism, opening the door to a new generation of logic, sensor, and data storage technologies. Here, we demonstrate an effective approach to magneto-ionically and

Graded Magnetic Materials

May 17, 2021
Lorenzo Fallarino, Brian Kirby, Eric E. Fullerton
Graded magnetic materials represent a promising new avenue in modern material science from both fundamental and application points of view. Over the course of the last few years, remarkable results have been obtained in (epitaxial) heterostructures based

Strong Ferromagnetism Achieved via Breathing Lattices in Atomically Thin Cobaltites

January 27, 2021
Sisi Li, Qinghua Zhang, Shan Lin, Xiahan Sang, Ryan F. Need, Manuel A. Roldan, Wenjun Cui, Zhiyi Hu, Qiao Jin, Shuang Chen, Jiali Zhao, Jia-Ou Wang, Jiesu Wang, Meng He, Chen Ge, Can Wang, Hui-Bin Lu, Zhenping Wu, Haizhong Guo, Xin Tong, Tao Zhu, Brian Kirby, Lin Gu, Kui-juan Jin, Er-Jia Guo
Low-dimensional quantum materials that retain strong ferromagnetism down to monolayer thickness hold great potential for spintronic applications. However, ferromagnetism in the transition metal oxides decays severely when the thickness is scaled to the

Observation of Anti-Damping Spin-Orbit Torques Generated by In-Plane and Out-of-Plane Spin Polarizations in MnPd 3

December 16, 2020
Mahendra DC, Ding-Fu Shao, Vincent D.-H. Hou, Patrick Quarterman, Ali Habiboglu, Brooks Venuti, Masashi Miura, Brian Kirby, Arturas Vailionis, Chong Bi, Xiang Li, Fen Xue, Yen-Lin Huang, Yong Deng, Shy-Jay Lin, Wilman Tsai, Serena Eley, Weigang Wang, Julie A. Borchers, Evgeny Y. Tsymbal, Shan X. Wang
High spin-orbit torques (SOTs) generated by topological materials and heavy metals interfaced with a ferromagnetic layer show promise for next generation magnetic memory and logic devices. SOTs generated from the in-plane spin polarization along y-axis

Differentiation between Strain and Charge Mediated Magnetoelectric Coupling in La 0.7 Sr 0.3 MnO 3 /Pb(Mg 1/3 Nb 2/3) d0.7^Ti 0.3 O 3 (001)

June 17, 2020
T. Bhatnagar-Schoffmann, Emmanuel Kentzinger, A. Sarkar, P. Schoffmann, Q. Lan, L. Jin, A. Kovacs, Alexander Grutter, Brian Kirby, R. Beerwerth, M. Waschk, Annika Stellhorn, U. Rucker, R. E. Dunin-Borkowski, Th. Bruckel
Magnetoelectric (ME) coupling in La 0.7 Sr 0.3 MnO 3 /Pb(Mg 1/3 Nb 2/3) d0.7^Ti 0.3 O 3 (LSMO/PMN-PT (001)) has been probed in the past years to identify the underlying mechanism behind it. PMN-PT, which is well known for its excellent piezoelectric

Magnetic Properties and Electronic Origin of the Interface between Dilute Magnetic Semiconductors with Orthogonal Magnetic Anisotropy

May 15, 2020
Ryan F. Need, Seul-Ki Bac, Xinyu Liu, Sanghoon Lee, Brian Kirby, Margaret Dobrowolska, Jacek Kossut, Jacek K. Furdyna
Controlling changes in magnetic anisotropy across epitaxial film interfaces is an important prerequisite for many spintronic devices. For the canonical dilute magnetic semiconductor GaMnAs, magnetic anisotropy is highly tunable through strain and doping

Impact of Growth Kinetics on the Interface Morphology and Magnetization in La 1/3 Sr 2/3 FeO 3 /La 2/3 Sr 1/3 MnO 3 Heterostructures

April 17, 2020
M. Waschk, A. Sarkar, J. Barthel, J. Voigt, S. Schroder, P. Zakalek, M. Schmitz, Brian Kirby, S. Putter, J. Schubert, T. Bruckel
The ability to create atomically perfect, epitaxial heterostructures of correlated complex perovskite oxides using state-of-art thin film deposition techniques has generated new physical phenomena at engineered interfaces. Here we report on the impact of

Correlation-Driven Eightfold Magnetic Anisotropy in a Two-Dimensional Oxide Monolayer

April 10, 2020
Zhangzhang Cui, Alexander Grutter, Hua Zhou, Hui Cao, Yongqi Dong, Dustin A. Gilbert, Jingyuan Wang, Yi-Sheng Liu, Jiaji Ma, Zhenpeng Hu, Jinghua Guo, Jing Xia, Brian Kirby, Padraic Shafer, Elke Arenholz, Hanghui Chen, Xiaofang Zhai, Yalin Lu
Engineering magnetic anisotropy (MA) in two-dimensional (2D) ferromagnetic materials has enormous scientific and technological implications. The uniaxial anisotropy universally exhibited by 2D ferromagnetic materials has only two stable spin directions

Strain-Induced Majority Carrier Inversion in Ferromagnetic Epitaxial LaCoO^d3-d Thin Films

March 4, 2020
Vipul Chaturvedi, Jeff Walter, Arpita Paul, Alexander Grutter, Brian Kirby, Jong Seok Jeong, Hua Zhou, Zhan Zhang, Biqiong Yu, Martin Greven, K. Andre Mkhoyan, Turan Birol, Chris Leighton
Tensile-strained LaCoO 3-δ thin films are ferromagnetic, in sharp contrast to the zero-spin bulk, although no clear consensus has emerged as to the origin of this phenomenon. While magnetism has been heavily studied, relatively little attention has been

Dysprosium Iron Garnet Thin Films with Perpendicular Magnetic Anisotropy on Silicon

January 1, 2020
Jackson J. Bauer, Ethan R. Rosenberg, Subhajit Kundu, K. Andre Mkhoyan, Patrick Quarterman, Alexander Grutter, Brian Kirby, Julie Borchers, Caroline A. Ross
Magnetic insulators, such as the rare-earth iron garnets, are promising materials for energy-efficient spintronic memory and logic devices, and their anisotropy, magnetization and other properties can be tuned over a wide range through selection of the

Emergent Magnetic State in (111)-Oriented Quasi-Two-Dimensional Spinel Oxides

December 11, 2019
Xiaoran Liu, Sobhit Singh, Brian Kirby, Zhicheng Zhong, Yanwei Cao, Banabir Pal, Mikhail Kareev, Srimanta Middey, John W. Freeland, Padraic Shafer, Elke Arenholz, David Vanderbilt, Jak Chakhalian
We report on the emergent magnetic state of (111)-oriented CoCr 2 O 4 ultrathin films sandwiched by Al 2 O 3 in the quantum confined geometry. At the two-dimensional crossover, polarized neutron reflectometry reveals an anomalous enhancement of the total

Spin Seebeck Imaging of Spin-Torque Switching in Antiferromagnetic Pt/NiO Heterostructures

October 22, 2019
Isaiah Gray, Takahiro Moriyama, Nikhil Sivadas, Gregory M. Stiehl, John T. Heron, Ryan F. Need, Brian Kirby, David H. Low, Katja Nowack, Darrell G. Schlom, Daniel C. Ralph, Teruo Ono, Gregory D. Fuchs
We demonstrate the spin Seebeck microscope as a sensitive method for imaging in-plane antiferromagnetic order in thin films. Recently, antidamping spin-orbit torques have been used to reorient Neel order in antiferromagnetic devices. Although the readout

Using Structural Phase Transitions to Enhance the Coercivity of Ferromagnetic Films

October 17, 2019
Ryan F Need, Josh Lauzier, Logan Sutton, Brian J Kirby, Jose de la Venta
Storing information in magnetic recording technologies requires careful optimization of the recording media's magnetic properties. For example, heat-assisted magnetic recording (HAMR) relies on a pre-recording heating step that momentarily lowers the

Ultrathin Interfacial Layer with Suppressed Room Temperature Magnetization in Magnesium Aluminum Ferrite Thin Films

September 24, 2019
Jacob J. Wisser, Satoru Emori, Lauren Riddiford, Aaron Altman, Peng Li, Krishnamurthy Mahalingam, Brittany T. Urwin, Brandon M. Howe, Michael R. Page, Alexander Grutter, Brian Kirby, Yuri Suzuki
Low-damping magnetic oxide thin films with small thicknesses are essential for efficient insulator spintronic devices, particularly those driven by spin torques effects. Here, we investigate depth-resolved compositional and magnetic properties of epitaxial

Effect of Oxygen Stoichiometry on the Magnetization Profiles and Negative Magnetization in LSMO Thin Films

September 14, 2019
Robbyn Trappen, Alexander Grutter, Chih-Yeh Huang, Aubrey Penn, Navid Mottaghi, Saeed Yousefi, Allison Haertter, Shalini Kumari, James LeBeau, Brian Kirby, Mikel B. Holcomb
The depth dependent magnetization in thin film oxygen stoichiometric and oxygen deficient La 0.7 Sr 0.3 MnO 3 is investigated by using polarized neutron reflectivity. The stoichiometric sample shows enhanced interfacial magnetization relative to the rest

Nanoscale Ferroelastic Twins Formed in Strained LaCoO 3 Films

March 29, 2019
Er-Jia Guo, Ryan Desautels, David Keavney, Manuel A. Roldan, Brian Kirby, Dongkyu Lee, Zhaoliang Liao, Timothy Charlton, Andreas Herklotz, T. Zac Ward, Michael R. Fitzsimmons, Ho Nyung Lee
The formation of twinning domains has been established as a major mechanism to accommodate epitaxial strain in rhombohedral ferroelastic oxide thin films. The elastic energy can be released at the expense of high interfacial energy at the domain boundaries

Exploring Interfacial Exchange Coupling and Sublattice Effect in Heavy Metal/Ferrimagnetic Insulator Heterostructures using Hall Measurements, X-Ray Magnetic Circular Dichroism, and Neutron Reflectometry

March 4, 2019
Qiming Shao, Alexander Grutter, Yawen Liu, Guoqiang Yu, Chao-Yao Yang, Dustin A. Gilbert, Elke Arenholz, Padraic Shafer, Xiaoyu Chi, Chi Tang, Mohammed Aldosary, Aryan Navabi, Qing Lin He, Brian Kirby, Jing Shi, Kang L. Wang
Ferrimagnetic insulators (FMIs), such as rare-earth iron garnets, are of considerable interest for low-power spintronics due to low Gilbert damping and the absence of free charge carriers. FMIs are also promising candidate materials for high-frequency

Phonon Localization in Heat Conduction

December 21, 2018
M. N. Luckyanova, J. Mendoza, H. Lu, B. Song, S. Huang, J. Zhou, M. Li., Y. Dong, H. Zhou, J. Garlow, L. Wu, Brian Kirby, Alexander Grutter, Alex A. Puretzky, Y. Zhu, M. S. Dresselhaus, A. Gossard, G. Chen
We report localization-like behavior in phonon heat conduction observed both in measurement of the thermal conductivities of GaAs/AlAs superlattice (SL) thin films with interfacial disorder caused by ErAs nanodots randomly distributed at the interfaces