Anomalous stabilization in a spin-transfer system at high spin polarization

TL;DR

This paper investigates how the angular dependence of spin-transfer torque efficiency affects switching behavior in nanoscale ferromagnets, revealing an anomalous region at high spin polarization that distinguishes different theoretical models.

Contribution

It demonstrates that switching diagrams are highly sensitive to the form of the spin-transfer efficiency factor, especially at high polarization, and proposes a method to experimentally differentiate models.

Findings

Switching diagrams depend on the angular form of g(θ).

Anomalous regions appear at high spin polarization in the Slonczewski model.

The configuration can distinguish between different g(θ) models.

Abstract

Switching diagrams of nanoscale ferromagnets driven by a spin-transfer torque are studied in the macrospin approximation. We consider a disk-shaped free layer with in-plane easy axis and external magnetic field directed in-plane at 90 degrees to that axis. It is shown that this configuration is sensitive to the angular dependence of the spin-transfer efficiency factor and can be used to experimentally distinguish between different forms of $g(\theta)$, in particular between the original Slonczewski form and the constant $g$ approximation. The difference in switching diagrams is especially pronounced at large spin polarizations, with the Slonczewski case exhibiting an anomalous region.