A Quantum Approach of Meso-Magnet Dynamics with Spin Transfer Torque

TL;DR

This paper develops a quantum theoretical framework for meso-magnet dynamics influenced by spin transfer torque, incorporating quantum fluctuations and corrections to classical electron transport models.

Contribution

It introduces a quantum master equation approach in the spin coherent state representation, linking quantum magnetization dynamics with electron transport and quantum corrections.

Findings

Quantum master equation describes magnetization dynamics with spin transfer torque.

In the large spin limit, dynamics follow Hamilton-Jacobi equations.

Quantum corrections modify electron transport properties.

Abstract

We present a theory of magnetization dynamics driven by spin-polarized current in terms of the quantum master equation. In the spin coherent state representation, the master equation becomes a Fokker-Planck equation, which naturally includes the spin transfer and quantum fluctuation. The current electron scattering state is correlated to the magnet quantum states, giving rise to quantum correction to the electron transport properties in the usual semiclassical theory. In the large spin limit, the magnetization dynamics is shown to obey the Hamilton-Jacobi equation or the Hamiltonian canonical equations.