Optimization of the current pulse for spin-torque switches

TL;DR

This paper derives the optimal current pulse profile for spin-torque switching in nanomagnets, showing it nearly doubles the minimal critical current and depends logarithmically on temperature and switching probability.

Contribution

It proves that the optimal current profile is the time-reversed relaxation trajectory, providing a theoretical basis for efficient spin-torque switching optimization.

Findings

Optimal current nearly twice the critical current

Pulse duration depends logarithmically on temperature

Trajectory is the time-reversed relaxation path

Abstract

We address optimization of the spin current intensity profile needed to achieve spin torque switching of a nanomagnet. For systems with Ohmic dissipation we prove that the optimal current drives the magnetization along the trajectory, which is exact time-reversed replica of the relaxation trajectory towards the equilibrium. In practice it means that the optimal current is very nearly {\em twice} the minimal critical current needed to switch the magnet. Pulse duration of such an optimal current is a slow logarithmic function of temperature and the required probability of switching.