Large Barocaloric Effect with High Pressure-Driving Efficiency in a Hexagonal MnNi0.77Fe0.23Ge Alloy

Abstract
The hydrostatic pressure is expected to be an effective knob to tune the magnetostructural phase transitions of hexagonal MM'X alloys (M and M' denote transition metals and X represents main group elements). We perform magnetization measurements under hydrostatic pressure on an MM'X martensitic MnNi20.77Fe0.23Ge alloy. The magnetostructural transition temperature can be efficiently tuned to lower temperatures by applying moderate pressures, with a giant shift rate of -151 K/GPa. A temperature span of 30 K is obtained under the pressure, within which a large magnetic entropy change of -23 J⋅kg-1K-1 in a field change of 5 T is induced by the mechanical energy gain due to the large volume change. Meanwhile, a decoupling of structural and magnetic transitions is observed at low temperatures when the martensitic transition temperature is lower than the Curie temperature. These results show a multi-parameter tunable caloric effect that benefits the solid-state cooling.

Citation
Zeng, Q., Shen, J., Liu, E., Xi, X., Wang, W., Wu, G., & Zhang, X. (2020). Large Barocaloric Effect with High Pressure-Driving Efficiency in a Hexagonal MnNi0.77Fe0.23Ge Alloy. Chinese Physics Letters, 37(7), 076101. doi:10.1088/0256-307x/37/7/076101

Acknowledgements
Supported by the National Natural Science Foundation of China (Grant No. 51722106), the National Key R&D Program of China (Grant No. 2019YFA0704904), Users with Excellence Program of Hefei Science Center CAS (Grant No. 2019HSC-UE009), and Fujian Institute of Innovation, Chinese Academy of Sciences.

Publisher
IOP Publishing

Journal
Chinese Physics Letters

DOI
10.1088/0256-307X/37/7/076101

arXiv
2106.02903

Additional Links
https://iopscience.iop.org/article/10.1088/0256-307X/37/7/076101

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