Magnetization switching in superlattice via thermal spin transfer torque

摘要

We theoretically investigate the switching characteristics of ferromagnets in the superlattice-like magnetic tunnel junction devices due to temperature bias. The critical switching spin current obstructs the anomaly flipping of magnetization in the stable condition of operation. We exploit the optical analog of anti-reflection in MTJ device design to harness its boxcar transmission feature. Using the non-equilibrium Green’s function spin transport formalism, we analyze the thermal spin-transfer torque switching in normal and anti-reflected superlattice configurations. It is observed that the operating temperature for complete flipping of magnetization in the case of anti-reflected superlattice is quite smaller than the normal superlattice. We also evaluate the thermal tunnel magnetoresistance (TMR) of both the device configurations and conclude that the switching and TMR ratio are the two different phenomena when a device operates on the temperature gradient alone. The discussed temperature variation is practically achievable with localized short laser pulses.