Mastering hysteresis in magnetocaloric materials

TL;DR

This paper explores the causes of hysteresis in magnetocaloric materials and proposes strategies to reduce it, aiming to improve the efficiency of magnetic refrigeration technology.

Contribution

It provides a detailed analysis of hysteresis mechanisms and develops methods to mitigate hysteresis in key magnetocaloric material classes.

Findings

Identified fundamental factors contributing to thermal hysteresis.

Developed strategies to partially overcome hysteresis in selected materials.

Enhanced understanding of hysteresis effects on magnetic cooling efficiency.

Abstract

Hysteresis is more than just an interesting oddity, which occurs in materials with a first-order transition. It is a real obstacle on the path from existing lab-scale prototypes of magnetic refrigerators towards commercialization of this potentially disruptive cooling technology. Indeed, the reversibility of the magnetocaloric effect, being essential for magnetic heat pumps, strongly depends on the width of the thermal hysteresis and therefore it is necessary to understand the mechanisms causing hysteresis and to find solutions how to minimize losses associated with thermal hysteresis in order to maximize the efficiency of magnetic cooling devices. In this work, we discuss fundamental aspects, which can contribute to thermal hysteresis and we are developing strategies for at least partially overcoming the hysteresis problem in some selected classes of magnetocaloric materials with large application potential. Doing so, we refer to the most relevant classes of magnetic refrigerants La-Fe-Si-, Heusler- and Fe2P-type compounds.