Realization of small intrinsic hysteresis with large magnetic entropy change in La0.8Pr0.2(Fe0.88Si0.10Al0.02)13 by controlling itinerant-electron characteristics

Abstract

Tuning of phase-transition characteristics in La(FexSi1−x)13 was conducted in view of the correlation between microscopic itinerant electron natures and macroscopic thermodynamic (magnetocaloric) quantities. To realize a small hysteresis loss QH accompanied by a large magnetic entropy change ΔSM in La(FexSi1−x)13, two types of modulation based on itinerant electron characteristics, namely, the Fermi-level shift and the magnetovolume effect were combined by complex partial substitution of Al and Pr. Ab-initio calculations predict the reduction of a transition hysteresis owing to the Fermi-level shift after partial substitution of Al. On the other hand, the chemical pressure arisen from partial substitution of Pr enhances ΔSM through magnetovolume effect. The selective enhancement of ΔSM apart from QH by the magnetovolume effect is well explained by the phenomenological Landau model. Consequently, ΔSM of La0.8Pr0.2(Fe0.88Si0.10Al0.02)13 is −18 J/kg K under a magnetic field change of 0–1.2 T, while the maximum value of QH becomes 1/6 of that for La(Fe0.88Si0.12)13.