Phys. Rev. B 76, 024404 (2007) [8 pages]Current-induced order parameter dynamics: Microscopic theory applied to Co∕Cu∕Co spin valvesSee Also: Erratum Received 18 December 2006; revised 20 May 2007; published 5 July 2007 Transport currents can alter order parameter dynamics and change steady states in superconductors, in ferromagnets, and in hybrid systems. In this paper, we present a scheme for fully microscopic evaluation of order parameter dynamics that is intended for application to nanoscale systems. The approach relies on time-dependent mean-field theory, on an adiabatic approximation, and on the use of nonequilibrium Green’s function theory to calculate the influence of a bias voltage across a system on its steady-state density matrix. We apply this scheme to examine the spin-transfer torques which drive magnetization dynamics in Co∕Cu∕Co spin-valve structures. Our microscopic torques are peaked near Co∕Cu interfaces, in agreement with most previous pictures, but surprisingly act mainly on Co transition metal d orbitals rather than on s orbitals as generally supposed. © 2007 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevB.76.024404
DOI:
10.1103/PhysRevB.76.024404
PACS:
85.75.−d, 71.15.Mb, 72.25.Ba
See AlsoErratum: P. M. Haney, D. Waldron, R. A. Duine, A. S. Núñez, H. Guo, and A. H. MacDonald, Erratum: Current-induced order parameter dynamics: Microscopic theory applied to Co∕Cu∕Co spin valves [Phys. Rev. B 76, 024404 (2007)], Phys. Rev. B 77, 059901 (2008). |
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