Magnetocaloric effect of gadolinium in high magnetic fields

摘要

The magnetocaloric effect of gadolinium has been measured directly in pulsed magnetic fields up to 62 T. The maximum observed adiabatic temperature change is Delta T-ad = 60.5 K, the initial temperature T-0 being just above 300 K. The field dependence of Delta T-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 Delta T-ad on T-0, at H = const. The familiar caret-shaped peak situated at T-0 = T-C becomes distinctly asymmetric, its high-temperature slope becoming more gentle and evolving into a broad plateau. For yet higher magnetic fields, mu H-0 greater than or similar to 140 T, calculations predict a complete disappearance of the maximum near T-C and an emergence of a new very broad maximum far above T-C.