Low relaxation rate in a low-Z alloy of iron

TL;DR

This paper demonstrates that adding vanadium to iron significantly reduces the Gilbert relaxation rate, indicating lower intrinsic magnetic damping due to decreased spin-orbit coupling in the alloy.

Contribution

It reports a novel low relaxation rate in a V-Fe alloy, surpassing pure iron, and explains the reduction through atomic number and spin-orbit coupling effects.

Findings

Relaxation rate reduced to 35±5 MHz with 27% V alloy

Lower relaxation rate than pure iron (57 MHz)

Spin-orbit coupling influences magnetic relaxation

Abstract

The longest relaxation time and sharpest frequency content in ferromagnetic precession is determined by the intrinsic (Gilbert) relaxation rate \emph{$G$}. For many years, pure iron (Fe) has had the lowest known value of $G=\textrm{57 Mhz}$ for all pure ferromagnetic metals or binary alloys. We show that an epitaxial iron alloy with vanadium (V) possesses values of $G$ which are significantly reduced, to 35$\pm$5 Mhz at 27% V. The result can be understood as the role of spin-orbit coupling in generating relaxation, reduced through the atomic number $Z$.