Phase diagram and magnetocaloric effect of CoMnGe_{1-x}Sn_{x} alloys

TL;DR

This study maps the phase diagram of CoMnGe_{1-x}Sn_{x} alloys, revealing a magnetostructural transition with significant entropy change but limited by thermal hysteresis, relevant for magnetocaloric applications.

Contribution

The paper presents the first phase diagram of CoMnGe_{1-x}Sn_{x} alloys and characterizes their magnetocaloric properties, highlighting the effects of Sn substitution.

Findings

Hysteretic magnetostructural phase transition observed for x=0.04 to 0.055

Maximum isothermal entropy change of 4.5 J/(K kg) at 1 Tesla

Large thermal hysteresis (~20 K) limits practical magnetocaloric use

Abstract

We propose the phase diagram of a new pseudo-ternary compound, CoMnGe_{1-x}Sn_{x}, in the range x less than or equal to 0.1. Our phase diagram is a result of magnetic and calometric measurements. We demonstrate the appearance of a hysteretic magnetostructural phase transition in the range x=0.04 to x=0.055, similar to that observed in CoMnGe under hydrostatic pressure. From magnetisation measurements, we show that the isothermal entropy change associated with the magnetostructural transition can be as high as 4.5 J/(K kg) in a field of 1 Tesla. However, the large thermal hysteresis in this transition (~20 K) will limit its straightforward use in a magnetocaloric device.