Direct Measurement of the Magnetocaloric Effect through Time-Dependent Magnetometry

• Author(s): Almeida, R. ; Amorim, C. ; Amaral, J. S. ; Araújo, J. P. ; Belo, J. H.
• Date: 2022
• Persistent ID: http://hdl.handle.net/10773/36179
• Origin: RIA - Repositório Institucional da Universidade de Aveiro
• Document Type: Journal article
• Language: English

Description

The magnetocaloric effect of a given material is typically assessed through indirect estimates of the isothermal magnetic entropy change, ΔSM. While estimating the adiabatic temperature difference, ΔTad, is more relevant from the standpoint of refrigeration device engineering, this requires specialized experimental setups. We here present an approach to directly measure ΔTad through time-dependent magnetometry in a commercial superconducting quantum interference device (SQUID) device. We use as reference material gadolinium under a 20-kOe field change, and compare our results with those of the literature. Under nonadiabatic experimental conditions, a remarkably similar ΔTad(T) curve profile is obtained; however, its peak amplitude is underestimated. With a simple compensation methodology we are able to further approximate the profile of the ΔTad(T) curve obtaining the peak amplitude, the maximizing temperature, and the FWHM within relative errors of -4%, -0.7%, and 11%, respectively. Our reported approach makes the measurement of both ΔSM(T) and ΔTad(T) possible with a single instrument, enabling accelerated progress towards new, competitive, and industry-ready materials.