Microscopic mechanism of the giant magnetocaloric effect in MnCoGe alloys probed by XMCD

TL;DR

This study investigates the microscopic origin of the giant magnetocaloric effect in MnCoGe alloys, revealing that Mn sub-lattice magnetization reduction drives the magneto-structural transition, with implications for magnetic cooling technologies.

Contribution

It combines XMCD and band structure calculations to identify the Mn sub-lattice magnetization reduction as the key factor behind the magneto-structural transition in MnCoGe.

Findings

Magnetization reduction in Mn sub-lattice causes phase transition.

Moment instability influences the magnetocaloric effect.

Element-specific magnetization insights obtained via XMCD.

Abstract

One important aspect of the magneto-structural transition in MnCoGe and related materials is the reduction in saturation magnetization from the orthorhombic to the hexagonal phase. Here, by combining an element specific magnetization probe such as x-ray magnetic circular dichroism and band structure calculations, we show that the magnetic moment instability between orthorhombic and hexagonal structures originates from a reduction in the Mn sub-lattice magnetization. The consequences of the moment instability for the magnetocaloric effect are discussed.