Enhancing spin-transfer torque through the proximity of quantum well states

Ioannis Theodonis, Alan Kalitsov, and Nicholas Kioussis
Phys. Rev. B 76, 224406 – Published 11 December 2007

Abstract

We predict that the spin-transfer, Ti,, and fieldlike, Ti,, components of the local spin torque are dramatically enhanced in double-barrier magnetic tunnel junctions. The spin-mixing enhancement is due to the energetic proximity of majority and minority quantum well states (QWSs) of different quantum numbers within the bias window. The local-spin-torque enhancement is not associated with a corresponding enhancement of the spin-polarized currents. Ti, exhibits a switch-on and switch-off steplike bias behavior when spin-polarized QWSs enter the bias window or exit the energy band, while Ti, changes sign between switch-on biases. The net T exhibits an anomalous angular behavior due to the bias interplay of the bilinear and biquadratic effective exchange couplings.

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  • Received 4 October 2007

DOI:https://doi.org/10.1103/PhysRevB.76.224406

©2007 American Physical Society

Authors & Affiliations

Ioannis Theodonis1,2,*, Alan Kalitsov1, and Nicholas Kioussis1

  • 1Department of Physics, California State University, Northridge, California 91330-8268, USA
  • 2Department of Physics, National Technical University, Zografou, Athens GR-15773, Greece

  • *ytheod@mail.ntua.gr

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Issue

Vol. 76, Iss. 22 — 1 December 2007

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