Current-Driven Magnetization Dynamics in Magnetic Multilayers

TL;DR

This paper introduces a quantum model for current-driven magnetic dynamics in multilayers, showing that excitations become incoherent and are better described by an effective temperature rather than classical precession, with similar switching behavior.

Contribution

It presents a quantum analog of the classical spin-torque model, highlighting the incoherent nature of excitations and proposing an effective temperature framework for current-driven magnetic dynamics.

Findings

Incoherent magnetic excitations at finite fields

Effective magnetic temperature describes excitations better than precession

Qualitative similarity in switching diagrams between models

Abstract

We develop a quantum analog of the classical spin-torque model for current-driven magnetic dynamics. The current-driven magnetic excitation at finite field becomes significantly incoherent. This excitation is described by an effective magnetic temperature rather than a coherent precession as in the spin-torque model. However, both the spin-torque and effective temperature approximations give qualitatively similar switching diagrams in the current-field coordinates, showing the need for detailed experiments to establish the proper physical model for current-driven dynamics.