Tuning the giant magnetocaloric effect in MnCoGe alloy with external pressure

Abstract

We report the effect of hydrostatic pressure on the magnetocaloric effect across the magneto-structural transition in an off-stoichiometric Mn34.5Co33.1Ge32.4 alloy. A very large isothermal entropy change of 38.95 J kg−1 K−1 is observed at nearly 303 K for a magnetic field excursion of 7 T at ambient pressure. The temperature of the peak entropy change and, thus, the working temperature range of the alloy drastically decrease by about 45 K with the application of a moderate hydrostatic pressure of 297 MPa. This shift is explained by correlating the results of x-ray diffraction measurements performed under high pressure for studying the structural aspect of the transition. Our results highlight the potential of the Mn–Co–Ge alloy system for multi-caloric applications in which the temperature change can be achieved by more than one external stimulus. The present work may also lead to future experiments, which study the response of multi-calorics driven by many external stimuli within the same experimental environment.