Giant Magnetocaloric Effect in Re-entrant Ferromagnet PrMn1.4Fe0.6Ge2

TL;DR

This study reports a giant magnetocaloric effect in PrMn1.4Fe0.6Ge2 due to multiple magnetic phase transitions, highlighting its potential for magnetic refrigeration near hydrogen liquefaction temperatures.

Contribution

First observation of giant magnetocaloric effect in PrMn1.4Fe0.6Ge2 linked to multiple magnetic phase transitions, with promising low-field application potential.

Findings

Multiple first order magnetic phase transitions detected.

Giant magnetocaloric effect observed at 25.5 K with 29.1 J/kg K for 7 T.

Significant MCE at low field change of 1 T, suitable for applications.

Abstract

Three first order magnetic phase transitions (FOMT) have been detected at TCPr, TNinter and TCinter over the temperature range from 5 K to 340 K at fields up to 9 T in PrMn1.4Fe0.6Ge2, and the magnetocaloric effect (MCE) around these transitions evaluated. The MCE of two FOMT from planar antiferromagnetism (AFl) to c-axis ferromagnetism (Fmc) around 168 K, and from the Fmc state to the c-axis AFmc state around 157 K have acceptable values compared with those of existing MCE systems. A giant magnetocaloric effect (GMCE) has been observed around 25.5 K associated with the field-induced FOMT from the AFmc to the Fmc+F(Pr) state with an additional Pr magnetic contribution. The MCE value 29.1 J/kg K with field change 7 T is comparable to and even larger than reported values for the best-performed MCE materials. In particular, the giant MCE value of 12.3 J/kg K obtained for the relatively small field change from 0 to 1 T is very beneficial for applications, and this, together with the small magnetic and thermal hysteresis, suggests that PrMn1.4Fe0.6Ge2 may be a promising candidate for magnetic refrigeration applications in the hydrogen liquefication temperature range.