Observation of Anomalous Spin Torque Generated by a Ferromagnet

Arnab Bose, D. D. Lam, S. Bhuktare, S. Dutta, H. Singh, Y. Jibiki, M. Goto, S. Miwa, and A. A. Tulapurkar

Phys. Rev. Applied 9, 064026 – Published 18 June 2018

Abstract

The spin-transfer-torque effect is predicted and subsequently demonstrated in a giant magnetoresistive (GMR) structure with current-perpendicular-to-plane geometry. In this work, we report that an unconventional out-of-plane magnetic field is created and exerts torque on a free magnet while in-plane current flows through the GMR sample. This strong effective magnetic field completely dominates the dampinglike torque which is expected to arise due to the anomalous Hall effect of a ferromagnet (analogous to the spin Hall effect in heavy metal). This anomalous magnetic field shows a very unusual angular dependence, which indicates broken-mirror symmetry in the lateral dimension. This anomalous torque may open an additional functionality for memory application.

Received 25 October 2017
Revised 12 March 2018

DOI:https://doi.org/10.1103/PhysRevApplied.9.064026

Physics Subject Headings (PhySH)

Anomalous Hall effect Ferromagnetism Magnetic anisotropy Spin current Spin torque

Magnetic multilayers Spin valves

P-symmetry

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Arnab Bose^1,*, D. D. Lam^2,†, S. Bhuktare¹, S. Dutta¹, H. Singh¹, Y. Jibiki², M. Goto², S. Miwa², and A. A. Tulapurkar^1,‡

¹Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
²Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan

^*arnabbose@ee.iitb.ac.in
^†Present address: Institute of Materials Science (IMS), VAST, Vietnam and Graduate University of Science and Technology (GUST), VAST, Vietnam.
^‡ashwin@ee.iitb.ac.in

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Vol. 9, Iss. 6 — June 2018

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Physical Review Applied