Strong magnetoelastic coupling in MnCoSi compounds studied in pulsed magnetic fields

Abstract

The orthorhombic MnCoSi compounds have been found to present a large magnetoelastic coupling, which is regarded as the source for the magnetocaloric effect (MCE) and the magnetostrictive effect. As a result, these compounds are potential materials for caloric applications such as solid-state refrigeration. In the present study, we offer fundamental insights in the magnetoelastic coupling in these compounds based on their structural, metamagnetic, and MCE behavior. The directly measured adiabatic temperature change ($\mathrm{\ensuremath{\Delta}}{T}_{\mathrm{ad}}$) in different initial temperatures (down to 18 K) and pulsed magnetic fields (up to 40 T) presents a moderate MCE performance (the maximum $\mathrm{\ensuremath{\Delta}}{T}_{\mathrm{ad}}=--3.1\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ for a field change of 13 T), which results from the metamagnetic behavior of these compounds. Furthermore, the magnetization measurements in pulsed (and static) magnetic fields indicate that the magnetoelastic coupling is significantly enhanced for increasing fields resulting in an improved saturation magnetization. The metamagnetic transition is continuously pushed to lower temperatures in higher fields. The phase diagram constructed from the experimental transition temperatures ${T}_{t}$ and the critical magnetic fields ${\ensuremath{\mu}}_{0}{H}_{\mathrm{cr}}$ indicate that the transition is terminated below 18 K and that ferromagnetism is stabilized for fields above 22.3 T. Our results provide unique insights into the strong magnetoelastic coupling under high pulsed magnetic fields, providing guidelines for the design of giant magnetocaloric materials for future caloric applications.