Direct Measurement of the Magnetocaloric Effect through Time-Dependent Magnetometry


The magnetocaloric effect of a given material is typically assessed through indirect estimates of the isothermal magnetic entropy change, delta S-M. While estimating the adiabatic temperature difference, delta T-ad, is more relevant from the standpoint of refrigeration device engineering, this requires specialized experimental setups. We here present an approach to directly measure delta T(ad )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 delta T-ad(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 delta T-ad(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 delta S-M(T) and delta T-ad(T) possible with a single instrument, enabling accelerated progress towards new, competitive, and industry-ready materials.






Almeida, R; Amorim, C; Amaral, JS; Araujo, JP; Belo, JH

nossos autores


This work was developed within the scope of the following projects financed by EEA grants via the project FBR_OC1_85 and by the Portuguese national funding agency for science, research and technology (FCT) : UIDB/50011/2020 and UIDP/50011/2020 (CICECO) , and PTDC/EME-TED/3099/2020 (IFIMUP) . J.H.B. also thanks FCT for the projects PTDC/FISMAC/31302/2017 and CERN/FISTEC/0003/2019 and for his contract DL57/2016 reference SFRH-BPD-87430/2012.

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