Electric-field-induced magnetization changes in Co/Al2O3 granular multilayers

Ajeesh M. Sahadevan, Alan Kalitsov, Gopinadhan Kalon, Charanjit S. Bhatia, Julian Velev, and Hyunsoo Yang
Phys. Rev. B 87, 014425 – Published 24 January 2013

Abstract

We study experimentally the effect of electric field on the magnetization of Co/Al2O3 granular multilayers. We observe two distinct regimes: (a) low-field regime when the net magnetization of the system changes in a reversible way with the applied electric field and (b) high-field regime when the magnetization decreases irreversibly. The former is attributed to the changes in the relative 3dorbital occupation of the minority and majority bands in the Co granules. A theoretical model has been developed to explain the electric-field-induced changes in the band structure of the granular system and hence the magnetic moment. The latter result may be understood assuming the electric field induces oxygen migration from Al2O3 to the Co granules, since an increase in oxidation state of the Co granules is shown, through ab initio calculations, to give rise to a reduced magnetization of the system.

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  • Received 19 June 2012

DOI:https://doi.org/10.1103/PhysRevB.87.014425

©2013 American Physical Society

Authors & Affiliations

Ajeesh M. Sahadevan1, Alan Kalitsov2, Gopinadhan Kalon1, Charanjit S. Bhatia1, Julian Velev2, and Hyunsoo Yang1,*

  • 1Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576, Singapore
  • 2Department of Physics, University of Puerto Rico, San Juan, Puerto Rico 00931, USA

  • *eleyang@nus.edu.sg

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Vol. 87, Iss. 1 — 1 January 2013

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