Enhanced tunnel magnetoresistance in a spinel oxide barrier with cation-site disorder

Hiroaki Sukegawa, Yoshio Miura, Shingo Muramoto, Seiji Mitani, Tomohiko Niizeki, Tadakatsu Ohkubo, Kazutaka Abe, Masafumi Shirai, Koichiro Inomata, and Kazuhiro Hono
Phys. Rev. B 86, 184401 – Published 2 November 2012

Abstract

We report enhanced tunnel magnetoresistance (TMR) ratios of 188% (308%) at room temperature and 328% (479%) at 15 K for cation-site-disordered MgAl2O4-barrier magnetic tunnel junctions (MTJs) with Fe (Fe0.5Co0.5 alloy) electrodes, which exceed the TMR ratios theoretically calculated and experimentally observed for ordered spinel barriers. The enhancement of TMR ratios is attributed to the suppression of the so-called band-folding effect in ordered spinel MTJs [Phys. Rev. B 86, 024426 (2012)]. First-principles calculations describe a dominant role of the oxygen sublattice for spin-dependent coherent tunneling, suggesting a mechanism of coherent tunneling occurring even in the disordered systems.

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  • Received 14 July 2012

DOI:https://doi.org/10.1103/PhysRevB.86.184401

©2012 American Physical Society

Authors & Affiliations

Hiroaki Sukegawa1,*, Yoshio Miura2, Shingo Muramoto2, Seiji Mitani1, Tomohiko Niizeki1, Tadakatsu Ohkubo1, Kazutaka Abe2, Masafumi Shirai2, Koichiro Inomata1, and Kazuhiro Hono1

  • 1National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba 305-0047, Japan
  • 2Research Institute of Electrical Communication (RIEC) and Center for Spintronics Integrated Systems (CSIS), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan

  • *sukegawa.hiroaki@nims.go.jp

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Issue

Vol. 86, Iss. 18 — 1 November 2012

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