Exploring interfacial exchange coupling and sublattice effect in heavy metal/ferrimagnetic insulator heterostructures using Hall measurements, x-ray magnetic circular dichroism, and neutron reflectometry

Qiming Shao, Alexander Grutter, Yawen Liu, Guoqiang Yu, Chao-Yao Yang, Dustin A. Gilbert, Elke Arenholz, Padraic Shafer, Xiaoyu Che, Chi Tang, Mohammed Aldosary, Aryan Navabi, Qing Lin He, Brian J. Kirby, Jing Shi, and Kang L. Wang

Phys. Rev. B 99, 104401 – Published 4 March 2019

Abstract

We use temperature-dependent Hall measurements to identify contributions of spin Hall, magnetic proximity, and sublattice effects to the anomalous Hall signal in heavy metal/ferrimagnetic insulator heterostructures with perpendicular magnetic anisotropy. This approach enables detection of both the magnetic proximity effect onset temperature and the magnetization compensation temperature and provides essential information regarding the interfacial exchange coupling. Onset of a magnetic proximity effect yields a local extremum in the temperature-dependent anomalous Hall signal, which occurs at higher temperature as magnetic insulator thickness increases. This magnetic proximity effect onset occurs at much higher temperature in Pt than W. The magnetization compensation point is identified by a sharp anomalous Hall sign change and divergent coercive field. We directly probe the magnetic proximity effect using x-ray magnetic circular dichroism and polarized neutron reflectometry, which reveal an antiferromagnetic coupling between W and the magnetic insulator. Finally, we summarize the exchange-coupling configurations and the anomalous Hall-effect sign of the magnetized heavy metal in various heavy metal/magnetic insulator heterostructures.

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Received 15 August 2018
Revised 15 February 2019

DOI:https://doi.org/10.1103/PhysRevB.99.104401

Physics Subject Headings (PhySH)

Spintronics

Magnetic insulators

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Qiming Shao^1,*, Alexander Grutter², Yawen Liu³, Guoqiang Yu^1,4, Chao-Yao Yang¹, Dustin A. Gilbert^2,5, Elke Arenholz⁶, Padraic Shafer⁶, Xiaoyu Che¹, Chi Tang³, Mohammed Aldosary^3,9, Aryan Navabi¹, Qing Lin He^1,7, Brian J. Kirby², Jing Shi³, and Kang L. Wang^1,8,*

¹Department of Electrical and Computer Engineering, University of California, Los Angeles, California 90095, USA
²NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA
³Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
⁴Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
⁵Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
⁶Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
⁷International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
⁸Department of Physics and Astronomy, Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, USA
⁹Department of Physics and Astronomy, King Saud University, Riyadh 11451, Saudi Arabia

^*Corresponding authors: sqm@ucla.edu; wang@seas.ucla.edu

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Vol. 99, Iss. 10 — 1 March 2019

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