The influence of structural asymmetries (barrier height and exchange splitting), as well as inelastic scattering (magnons and phonons) on the bias dependence of the spin transfer torque in a magnetic tunnel junction is studied theoretically using the free-electron model. We show that they modify the "conventional" bias dependence of the spin transfer torque, together with the bias dependence of the conductance. In particular, both structural asymmetries and bulk (inelastic) scattering add antisymmetric terms to the perpendicular torque (V and je |V|) while the interfacial inelastic scattering conserves the junction symmetry and only produces symmetric terms ( ⊃|V⊃| n, nN). The analysis of spin torque and conductance measurements displays a signature revealing the origin (asymmetry or inelastic scattering) of the discrepancy.
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2010 Nov 15
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics