On entropy change measurements around first order phase transitions in caloric materials

TL;DR

This paper discusses proper measurement protocols for accurately determining entropy changes during first order phase transitions in caloric materials, emphasizing the impact of protocol design on measurement accuracy.

Contribution

It introduces validated measurement protocols for accurate entropy change assessment in first order phase transitions, addressing common pitfalls in experimental procedures.

Findings

Improper protocols can lead to significant errors in entropy change estimation.

Proper protocols enable accurate assessment of entropy changes in both direct and inverse transitions.

Case studies on Cu-doped MnAs and FeRh demonstrate protocol effectiveness.

Abstract

In this work we discuss the measurement protocols for indirect determination of the isothermal entropy change associated with first order phase transitions in caloric materials. The magneto- structural phase transitions giving rise to giant magnetocaloric effects in Cu-doped MnAs and FeRh are used as case studies to exemplify how badly designed protocols may affect isothermal measure- ments and lead to incorrect entropy change estimations. Isothermal measurement protocols which allow correct assessment of the entropy change around first order phase transitions in both direct and inverse cases are presented.