Modulating the phase transition temperature of giant magnetocaloric thin films by ion irradiation

TL;DR

This study demonstrates that ion irradiation can effectively modulate the phase transition temperature of giant magnetocaloric thin films, expanding their usable temperature range for room-temperature magnetic refrigeration.

Contribution

It introduces a method to tune the transition temperature of magnetocaloric materials using ion irradiation, enabling broader application in refrigeration devices.

Findings

Transition temperature can be shifted by ion irradiation.

Ion-induced disorder and defects cause Tc modification.

Large temperature window (270-380 K) achieved for refrigeration.

Abstract

Magnetic refrigeration based on the magnetocaloric effect at room temperature is one of the most attractive alternative to the current gas compression/expansion method routinely employed. Nevertheless, in giant magnetocaloric materials, optimal refrigeration is restricted to the narrow temperature window of the phase transition (Tc). In this work, we present the possibility of varying this transition temperature into a same giant magnetocaloric material by ion irradiation. We demonstrate that the transition temperature of iron rhodium thin films can be tuned by the bombardment of ions of Ne 5+ with varying fluences up to 10 14 ions cm --2 , leading to optimal refrigeration over a large 270--380 K temperature window. The Tc modification is found to be due to the ion-induced disorder and to the density of new point-like defects. The variation of the phase transition temperature with the number of incident ions opens new perspectives in the conception of devices using giant magnetocaloric materials.