title: Anomalous bias dependence of spin torque in magnetic tunnel junctions.
abstract: We predict an anomalous bias dependence of the spin transfer torque parallel to the interface, Tparallel, in magnetic tunnel junctions, which can be selectively tuned by the exchange splitting. It may exhibit a sign reversal without a corresponding sign reversal of the bias or even a quadratic bias dependence. We demonstrate that the underlying mechanism is the interplay of spin currents for the ferromagnetic (antiferromagnetic) configurations, which vary linearly (quadratically) with bias, respectively, due to the symmetric (asymmetric) nature of the barrier. The spin transfer torque perpendicular to interface exhibits a quadratic bias dependence.
authors.affiliation: Department of Physics, California State University, Northridge, California 91330-8268, USA.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Theodonis
authors.forename: Nicholas
authors.initials: N
authors.lastname: Kioussis
authors.forename: Alan
authors.initials: A
authors.lastname: Kalitsov
authors.forename: Mairbek
authors.initials: M
authors.lastname: Chshiev
authors.forename: W H
authors.initials: WH
authors.lastname: Butler