Magnetocaloric effect of gadolinium in high magnetic fields

Abstract

The magnetocaloric effect of gadolinium has been measured directly in pulsed magnetic fields up to $62\phantom{\rule{0.16em}{0ex}}\mathrm{T}$. The maximum observed adiabatic temperature change is $\mathrm{\ensuremath{\Delta}}{T}_{\mathrm{ad}}=60.5\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, the initial temperature ${T}_{0}$ being just above $300\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The field dependence of $\mathrm{\ensuremath{\Delta}}{T}_{\mathrm{ad}}$ is found to follow the usual ${H}^{2/3}$ law, with a small correction in ${H}^{4/3}$. However, as $H$ is increased, a radical change is observed in the dependence of $\mathrm{\ensuremath{\Delta}}{T}_{\mathrm{ad}}$ on ${T}_{0}$, at $H=\mathrm{const}$. The familiar caret-shaped peak situated at ${T}_{0}={T}_{\mathrm{C}}$ becomes distinctly asymmetric, its high-temperature slope becoming more gentle and evolving into a broad plateau. For yet higher magnetic fields, ${\ensuremath{\mu}}_{0}H\ensuremath{\gtrsim}140\phantom{\rule{0.16em}{0ex}}\mathrm{T}$, calculations predict a complete disappearance of the maximum near ${T}_{\mathrm{C}}$ and an emergence of a new very broad maximum far above ${T}_{\mathrm{C}}$.