Origin of threshold current density for asymmetric magnetoresistance in Pt/Py bilayers

TL;DR

This paper investigates the threshold behavior of asymmetric magnetoresistance in Py/Pt bilayers, revealing that spin-torque-induced magnetization reduction causes the observed threshold in MR response.

Contribution

It introduces a micromagnetic simulation approach to identify spin-torque oscillation as the origin of the threshold in asymmetric MR.

Findings

Asymmetric MR increases linearly with current density below threshold.

Magnetic field suppresses asymmetric MR only above threshold.

Spin-torque oscillation reduces magnetization, causing threshold behavior.

Abstract

An asymmetric magnetoresistance (MR) is investigated in Py/Pt bilayers. The asymmetric MR linearly increases with current density up to a threshold, and increases more rapidly above the threshold. To reveal the origin of threshold behavior, we investigate the magnetic field dependence of the asymmetric MR. It is found that the magnetic field strongly suppresses the asymmetric MR only above the threshold current density. Micromagnetic simulation reveals that the reduction of magnetization due to the spin-torque oscillation can be the origin of the threshold behavior of asymmetric MR.