Detailed isofield calorimetry of La(Fe,Si,Mn)H reveals distributed magnetocaloric phase transitions

Florian Erbesdobler*, C. R. H. Bahl, Rasmus Bjørk, Kaspar Kirstein Nielsen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

We show that low ramp rate differential scanning calorimetry of the magnetocaloric material La ( Fe 11.47 Si 1.28 Mn 0.25 ) H 1.65 at different applied magnetic fields reveals the presence of distributed phase transitions. Experimentally, we find that with or without an applied magnetic field, samples show a distinct peak pattern in their heat capacity around the transition temperature ( T t ≈ 30 ° C), i.e., multiple heat capacity peaks occur as a function of sample temperature. Additionally, these reproducible patterns occur asymmetrically when heating and cooling. At finite applied fields higher than 0.15 T, we observe clearly distinguishable peaks of identical shape, albeit with different intensities. According to the latter, we re-identify the peaks under seven applied magnetic fields up to 1 T. We find that the peaks shift differently relative to each other as a function of field. In particular, for cooling experiments, the peak temperatures vary linearly in the field, although with different slopes. Through Bean–Rodbell (BR) modeling, we show that the experimentally observed behavior can be simulated by small decoupled variations in the BR parameters η and T 0, indicating a distributed composition of the magnetocaloric material.
Original languageEnglish
Article number095102
JournalJournal of Applied Physics
Volume127
Issue number9
Number of pages8
ISSN0021-8979
DOIs
Publication statusPublished - 2020

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