Dipolar field effect on microwave oscillation in a domain wall spin-valve

TL;DR

This study investigates how dipolar fields influence microwave generation in domain wall spin-valves, revealing the importance of dipole interactions and exchange length for optimizing microwave signals.

Contribution

It demonstrates the necessity of dipole-dipole interactions for microwave generation and highlights the role of exchange length in signal amplitude, guiding material selection for efficient devices.

Findings

Microwave generation requires dipole-dipole interaction in 180° domain walls.

Microwave voltage amplitude depends strongly on exchange length.

Materials with short exchange length are preferred for high-efficiency devices.

Abstract

We examined dipolar field effects on the microwave generation in the domain wall spin-valve by solving simultaneously the Landau-Lifshitz-Gilbert and Zhang-Levy-Fert diffusion equations. By numerically analyzing dipolar field dependence, we showed that the microwave generation needs the dipole-dipole interaction for a 180$^\circ$ domain wall and the amplitude of the microwave voltage signal depends strongly on the exchange length. In order to design a microwave generator using the domain wall spin-valve with high efficiency, we propose that the materials with short exchange length are preferred.