Wide temperature span of entropy change in first-order metamagnetic MnCo1-xFexSi

TL;DR

This study investigates MnCo1-xFexSi compounds, revealing a wide temperature span of entropy change due to metamagnetic transitions, making them promising for magnetic refrigeration near room temperature.

Contribution

It demonstrates the large temperature span of entropy change in MnCo1-xFexSi compounds caused by metamagnetic transitions, highlighting their potential for magnetic cooling applications.

Findings

Large negative magnetocaloric effect at low fields

Wide temperature span of entropy change (103 K at 5 T)

Emergence of spin-glass-like and antiferromagnetic states

Abstract

The crystal structure and magnetic properties of MnCoxFe1-xSi (x=0-0.5) compounds were investigated. With increasing Fe content, the unit cell changes anisotropically and the magnetic property evolves gradually: Curie temperature decreases continuously, the first-order metamagnetic transition from a low-temperature helical antiferromagnetic state to a high-temperature ferromagnetic state disappears gradually and then a spin-glass-like state and another antiferromagnetic state emerge in the low temperature region. The Curie transition leads to a moderate conventional entropy change. The metamagnetic transition not only yields a larger negative magnetocaloric effect at lower applied fields than in MnCoSi but also produces a very large temperature span (103 K for H=5 T) of delta S(T), which results in a large refrigerant capacity. These phenomena were explained in terms of crystal structure change and magnetoelastic coupling mechanism. The low-cost MnCo1-xFexSi compounds are promising candidates for near room temperature magnetic refrigeration applications because of the large isothermal entropy change and the wide working temperature span.