A microscopic model for current-induced switching of magnetization for half-metallic leads

TL;DR

This paper presents a microscopic, self-consistent model for current-induced magnetization switching in a half-metallic tunnel junction, capturing the voltage-dependent transition between magnetic states without classical approximations.

Contribution

It introduces a nonequilibrium spectral density approach within the Hubbard model to analyze magnetization switching microscopically.

Findings

Voltage can switch magnetization from antiparallel to parallel alignment.

Switching behavior aligns with the Slonczewski model.

The model predicts voltage-dependent switching without classical methods.

Abstract

We study the behaviour of the magnetization in a half-metallic ferromagnet/nonmagnetic insulator/ferromagnetic metal/paramagnetic metal (FM1/NI/FM2/PM) tunnel junction. It is calculated self-consistently within the nonequilibrium Keldysh formalism. The magnetic regions are treated as band ferromagnets and are described by the single-band Hubbard model. We developed a nonequilibrium spectral density approach to solve the Hubbard model approximately in the switching magnet. By applying a voltage to the junction it is possible to switch between antiparallel (AP) and parallel (P) alignment of the magnetizations of the two ferromagnets. The transition from AP to P occurs for positive voltages while the inverse transition from P to AP can be induced by negative voltages only. This behaviour is in agreement with the Slonczewski model of current-induced switching and appears self-consistently within the model, i.e. without using half-classical methods like the Landau-Lifshitz-Gilbert equation.