Current-induced microwave excitation of a domain wall confined in a magnetic wire with bi-axial anisotropy

TL;DR

This paper investigates how current can induce microwave oscillations in a confined magnetic domain wall with bi-axial anisotropy, revealing a breathing-mode excitation useful for microwave sources.

Contribution

It demonstrates the excitation of a breathing-mode in a confined domain wall via spin-transfer torque and explores its potential as a microwave oscillator.

Findings

Breathing-mode is induced above a threshold current density.

The breathing-mode frequency shows hysteresis due to confinement.

Domain wall resistance varies with its thickness, enabling microwave generation.

Abstract

We studied the current-induced magnetization dynamics of a domain wall confined in a magnetic wire with bi-axial anisotropy. We showed that above the threshold current density, breathing-mode excitation, where the thickness of the domain wall oscillates, is induced by spin-transfer torque. We found that the breathing-mode can be applied as a source of microwave oscillation because the resistance of the domain wall is a function of the domain wall thickness. In a current sweep simulation, the frequency of the breathing-mode exhibits hysteresis because of the confinement.