Relation between unidirectional spin Hall magnetoresistance and spin current-driven magnon generation

TL;DR

This study reveals a strong correlation between unidirectional spin Hall magnetoresistance and magnon generation driven by spin currents, showing that USMR is primarily influenced by dipolar magnons across a wide temperature range.

Contribution

It establishes a direct link between USMR and dipolar magnon density, highlighting the magnon-driven origin of USMR in ferromagnet/normal metal bilayers.

Findings

USMR depends on magnon density and scales with it.

USMR and magnon population exhibit similar temperature dependence.

Dipolar magnons dominate the USMR response.

Abstract

We perform electronic measurements of unidirectional spin Hall magnetoresistance (USMR) in a Permalloy/Pt bilayer, in conjunction with magneto-optical Brillouin light spectroscopy of spin current-driven magnon population. We show that the current dependence of USMR closely follows the dipolar magnon density, and that both dependencies exhibit the same scaling over a large temperature range of 80-400 K. These findings demonstrate a close relationship between spin current-driven magnon generation and USMR, and indicate that the latter is likely dominated by the dipolar magnons.