Mechanisms of energy-efficient magnetization switching in a bistable nanowire

Theoretical calculations of optimal control paths minimizing the energy cost of the magnetization reversal in 1D magnetic nanowires are presented. The energy-efficient reversal mechanism is studied as a function of the nanowire length and Gilbert damping parameter. For short nanowires, the optimal reversal mechanism corresponds to a uniform rotation of magnetization. If the length of the wire exceeds a certain critical length defined by the material parameters, switching time and damping, a standing spin wave emerges during magnetization switching. Comparison between the calculated optimal control paths and minimum energy paths reveals that realization of high energy efficiency of switching does not necessarily translate to the minimization of the energy barrier between the target magnetic states.