Influence of interfacial magnons on spin transfer torque in magnetic tunnel junctions

The role of interfacial electron-magnon interaction in a noncollinear magnetic tunnel junction is investigated using the transfer Hamiltonian method. It is shown that the interfacial electron-magnon scattering modifies the bias dependence of both components of the spin-transfer torque. In particular, we find that at low temperature, the magnons emission adds a quadratic contribution and at finite temperature, both quadratic and linear terms appear. These contributions can explain recent experimental results on the bias dependence of spin-transfer torque.