Tunable magnetization damping in transition metal ternary alloys

TL;DR

This paper demonstrates that alloying Permalloy with transition metals, especially osmium, significantly enhances magnetization damping, reducing magnetization precession and potentially improving magnetic device performance.

Contribution

It introduces a method to tune magnetization damping in Permalloy by alloying with transition metals, highlighting osmium's effectiveness in increasing damping.

Findings

Damping increases monotonically with Os concentration up to 9%.

Alloying with Os suppresses magnetization and enhances in-plane anisotropy.

Other transition metals also increase damping but less effectively than Os.

Abstract

We show that magnetization damping in Permalloy, Ni80Fe20 (``Py''), can be enhanced sufficiently to reduce post-switching magnetization precession to an acceptable level by alloying with the transition metal osmium (Os). The damping increases monotonically upon raising the Os-concentration in Py, at least up to 9% of Os. Other effects of alloying with Os are suppression of magnetization and enhancement of in-plane anisotropy. Magnetization damping also increases significantly upon alloying with the five other transition metals included in this study (4d-elements: Nb, Ru, Rh; 5d-elements: Ta, Pt) but never as strongly as with Os.