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Search Publications by: Purnima Balakrishnan (Fed)

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Displaying 1 - 17 of 17

Extensive Hydrogen Incorporation is not Necessary for Superconductivity in Topotactically Reduced Nickelates

August 27, 2024
Author(s)
Purnima Balakrishnan, Dan Segedin, Lin Chow, P. Quarterman, Shin Muramoto, Mythili Surendran, Ranjan Patel, Harrison LaBollita, Grace Pan, Qi Song, Yang Zhang, Ismail El Baggari, Koushik Jagadish, Yu-Tsun Shao, Berit Goodge, Lena Kourkoutis, Srimanta Middey, Antia Botana, Jayakanth Ravichandran, A. Ariando, Julia A. Mundy, Alexander Grutter
A key open question in the study of layered superconducting nickelate films is the role that hydrogen incorporation into the lattice plays in the appearance of the superconducting state. Due to the challenges of stabilizing highly crystalline square planar

Coexistence of Superconductivity and Antiferromagnetism in Topological Magnet MnBi2Te4 Films

July 3, 2024
Author(s)
Wei Yuan, Zi-Jie Yan, Hemian Yi, Zihao Wang, Stephen Paolini, Yi-Fan Zhao, Ling-Jie Zhou, Annie G. Wang, Ke Wang, Thomas Prokscha, Zaher Salman, Andreas Suter, Purnima Balakrishnan, Alexander Grutter, Laurel E. Winter, John Singleton, Moses H. Chan, Cui-Zu Chang
The interface of two materials can harbor unexpected emergent phenomena. One example is interface-induced superconductivity. In this work, we employ molecular beam epitaxy to grow a series of heterostructures formed by stacking together two

Vertically Graded FeNi Alloys with Low Damping and a Sizeable Spin-Orbit Torque

June 14, 2024
Author(s)
Rachel Maizel, Shuang Wu, Purnima P. Balakrishnan, Alexander Grutter, Christy Kinane, Andrew Caruana, Prabandha Nakarmi, Bhuwan Nepal, David Smith, Youngmin Lim, Juila Jones, Wyatt Thomas, Jing Zhao, F. Michel, Tim Mewes, Satoru Emori
Energy-efficient spintronic devices require a large spin-orbit torque (SOT) and low damping to excite magnetic precession. In conventional devices with heavy-metal/ferromagnet bilayers, reducing the ferromagnet thickness to ∼1 nm enhances the SOT but drama

Reduction-Induced Magnetic Behavior in LaFeO3-d Thin Films

March 4, 2024
Author(s)
Nathan Arndt, Eitan Hershkovitz, Labdhi Shah, Kristoffer Kjaernes, Chao-Yao Yang, Purnima Balakrishnan, Mohammed Shariff, Shaun Tauro, Daniel Gopman, Brian Kirby, Alexander Grutter, Thomas Tybell, Honggyu Kim, Ryan Need
The effect of oxygen reduction on the magnetic properties of LaFeO3−δ (LFO) thin films was studied to better understand the viability of LFO as a candidate for magnetoionic memory. Differences in the amount of oxygen lost by LFO and its magnetic behavior

Emergent Ferromagnetism in CaRuo3/CaMnO3 (111)-Oriented Superlattices

February 17, 2024
Author(s)
Margaret Kane, Churna Bhandari, Megan Holtz, Purnima Balakrishnan, Alexander Grutter, Michael R. Fitzsimmons, Chao-Yao Yang, Sashi Satpathy, Durga Paudyal, Yuri Suzuki
The boundary between CaRuO3 and CaMnO3 is an ideal test bed for emergent magnetic ground states stabilized through interfacial electron interactions. In this system, nominally antiferromagnetic and paramagnetic materials combine to yield interfacial

First-Order Phase Transition versus Spin-State Quantum-Critical Scenarios in Strain-Tuned Epitaxial Cobaltite Thin Films

February 14, 2024
Author(s)
John Dewey, Vipul Chaturvedi, Tatiana Webb, Prachi Sharma, William Postiglione, P. Quarterman, Purnima Balakrishnan, Brian Kirby, Lucca Figari, Caroline Korostynski, Andrew Jacobson, Turan Birol, Rafael Fernandes, Abhay Pasupathy, Chris Leighton
Pr-containing perovskite cobaltites exhibit unusual valence transitions, coupled to coincident structural, spin-state, and metal-insulator transitions. Heteroepitaxial strain was recently used to control these phenomena in the model (Pr1−yYy )1−xCaxCoO3−δ

Interface-Induced Superconductivity in Magnetic Topological Insulators

February 9, 2024
Author(s)
Hemian Yi, Yi-Fan Zhao, Ying-Ting Chan, Jiaqi Cai, Ruobing Mei, Xianxin Wu, Zi-Jie Yan, Ling-Jie Zhou, Ruoxi Zhang, Zihao Wang, Stephen Paolini, Run Xiao, Ke Wang, Anthoney Richardella, John Singleton, Laurel Winter, Thomas Prokscha, Zaher Salman, Andreas Suter, Purnima Balakrishnan, Alexander Grutter, Moses Chan, Nitin Samarth, Xiaodong Xu, Weida Wu, Chao-Xing Liu, Cui-Zu Chang
The interface between two different materials can show unexpected quantum phenomena. In this study, we used molecular beam epitaxy to synthesize heterostructures formed by stacking together two magnetic materials, a ferromagnetic topological insulator (TI)

Controllable Conical Magnetic Structure and Spin-Orbit-Torque Switching in Symmetry-Broken Ferrimagnetic Films

January 23, 2024
Author(s)
Yaqin Guo, Jing Zhang, Purnima Balakrishnan, Alexander Grutter, Baishun Yang, Michael R. Fitzsimmons, Timothy Charlton, Haile Ambaye, Xu Zhang, Hanshen Huang, Zhi Huang, Jinyan Chen, Chenyang Guo, Xiufeng Han, Kang Wang, Hao Wu
Exploring and controlling chiral spin textures has attracted enormous interest from the perspective of fundamental research and spintronic applications. Here, we report the emergence of spiral spin states, bulk spin-orbit torque (SOT), and the

Exchange-Biased Quantum Anomalous Hall Effect

May 19, 2023
Author(s)
Peng Zhang, Purnima P. Balakrishnan, Christopher Eckberg, Peng Deng, Tomohiro Nozaki, Patrick Quarterman, Megan Holtz, Lei Pan, Sukong Chong, Eve Emmanouilidou, Ni Ni, Masashi Sahashi, Alexander Grutter, Kang L. Wang
The quantum anomalous Hall (QAH) effect is characterized by a dissipationless chiral edge state with a quantized Hall resistance at zero magnetic field. Manipulating the QAH state is of great importance in both the understanding of topological quantum

Tailoring the Magnetic Exchange Interaction in MnBi2Te4 Superlattices via the Intercalation of Ferromagnetic Layers

January 1, 2023
Author(s)
Peng Chen, Qi Yao, Junqi Xu, Qiang Sun, Alexander Grutter, Patrick Quarterman, Purnima P. Balakrishnan, Christy J. Kinane, Andrew J. Caruana, Sean Langridge, Ang Li, Barat Achinuq, Emily Heppell, Yuchen Ji, Shanshan Liu, Baoshan Cui, Jiuming Liu, Puyang Huang, Zhongkai Liu, Guoqiang Yu, Faxian Xiu, Thorsten Hesjedal, Jin Zou, Xiaodong Han, Haijun Zhang, Yumeng Yang, Xufeng Kou
The intrinsic magnetic topological insulator MnBi 2Te 4 (MBT) has provided a platform for the successful realization of exotic quantum phenomena. To broaden the horizons of MBT-based material systems, we intercalate ferromagnetic MnTe layers to construct

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

December 15, 2022
Author(s)
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

Engineering Magnetic Anisotropy and Emergent Multidirectional Soft Ferromagnetism in Ultrathin Freestanding LaMnO 3 Films

May 24, 2022
Author(s)
Qinwen Lu, Zhiwei Liu, Qun Yang, Hui Cao, Purnima P. Balakrishnan, Qing Wang, Long Cheng, Yalin Lu, Jian-Min Zuo, Hua Zhou, Patrick Quarterman, Shinichiro N. Muramoto, Alexander Grutter, Hanghui Chen, Xiaofang Zhai
Owing to their small coercive fields and weak magnetic anisotropy, soft ferromagnetic films are extremely useful for nanoscale devices that need to easily switch spin directions. However, they are rare, particularly when a film thickness is reduced to a

Magnetic Field-Induced Non-Trivial Electronic Topology in Fe 3-x GeTe 2

October 7, 2021
Author(s)
Juan Macy, Danilo Ratkovski, Purnima P. Balakrishnan, Mara Strungaru, Yu-Che Chiu, Aikaterini Flessa, Alex Moon, Wenkai Zheng, Ashley Weiland, Gregory T. McCandless, Julia Y. Chan, Govind S. Kumar, Michael Shatruk, Alexander Grutter, Julie Borchers, William D. Ratcliff, Eun S. Choi, Elton J. Santos, Luis Balicas
The anomalous Hall, Nernst and thermal Hall coefficients of the itinerant ferromagnet Fe 3−xGeTe 2 display several features upon cooling, like a reversal in the Nernst signal below T = 50 K pointing to a topological transition possibly associated to the