Experimental Investigation of Temperature-Dependent Gilbert Damping in Permalloy Thin Films

TL;DR

This study experimentally investigates how Gilbert damping in permalloy thin films varies with temperature, revealing distinct bulk and surface damping behaviors that enhance understanding of magnetization dynamics crucial for spintronics.

Contribution

The paper provides the first detailed experimental analysis of temperature-dependent Gilbert damping in permalloy films, identifying separate bulk and surface damping contributions.

Findings

Bulk damping decreases with decreasing temperature.

Surface damping peaks around 50 K.

Distinct behaviors of bulk and surface damping are observed.

Abstract

The Gilbert damping of ferromagnetic materials is arguably the most important but least understood phenomenological parameter that dictates real-time magnetization dynamics. Understanding the physical origin of the Gilbert damping is highly relevant to developing future fast switching spintronics devices such as magnetic sensors and magnetic random access memory. Here, we report an experimental study of temperature-dependent Gilbert damping in permalloy (Py) thin films of varying thicknesses by ferromagnetic resonance. From the thickness dependence, two independent contributions to the Gilbert damping are identified, namely bulk damping and surface damping. Of particular interest, bulk damping decreases monotonically as the temperature decreases, while surface damping shows an enhancement peak at the temperature of ~50 K. These results provide an important insight to the physical origin of the Gilbert damping in ultrathin magnetic films.