Spin-wave instability for parallel pumping in ferromagnetic thin films under oblique field

TL;DR

This paper theoretically investigates spin-wave instability thresholds in ferromagnetic thin films under oblique magnetic fields, revealing how the butterfly curve's cusp features vary with film thickness and oblique angle.

Contribution

It introduces a theoretical analysis of spin-wave instability thresholds considering oblique fields and identifies novel cusp features in thin films due to multiple standing modes.

Findings

Butterfly curve cusp position varies with oblique angle.

Multiple cusps appear in thin films indicating different standing modes.

General butterfly curve properties are stable across oblique angles.

Abstract

Spin-wave instability for parallel pumping is studied theoretically. The spin-wave instability threshold is calculated in ferromagnetic thin films under oblique field which has an oblique angle to the film plane. The butterfly curve of the threshold usually has a cusp at a certain value of the static external field. While the static field value of the cusp point varies as the oblique angle changes, the general properties of the butterfly curve show little noteworthy change. For very thin films, however, multiple cusps of the butterfly curve can appear due to different standing spin-wave modes, which indicate a novel feature for thin films under oblique field.