Itinerant Antiferromagnetism in FeMnP0.8Si0.2 Single Crystals

TL;DR

This study reports the growth and detailed characterization of FeMnP0.8Si0.2 single crystals, revealing unexpected itinerant antiferromagnetic order below 158 K and insights into their structural and electronic properties relevant for magnetocaloric applications.

Contribution

First demonstration of single crystal growth and comprehensive analysis of FeMnP0.8Si0.2, uncovering itinerant antiferromagnetism and site occupancy preferences in this compound.

Findings

Crystals exhibit itinerant antiferromagnetic order below 158 K.

No ferromagnetic behavior observed in magnetization curves.

Strong Mn site preference in the crystal structure.

Abstract

Compounds based on the Fe2P structure have continued to attract interest because of the interplay between itinerant and localized magnetism in a non-centrosymmetric crystal structure, and because of the recent developments of these materials for magnetocaloric applications. Here we report the growth and characterization of mm size single crystals of FeMnP0.8Si0.2. Single crystal x-ray diffraction, magnetization, resistivity, Hall and heat capacity data are reported. Surprisingly, the crystals exhibit itinerant antiferromagnetic order below 158 K with no hint of ferromagnetic behavior in the magnetization curves and with the spins ordered primarily in the ab plane. The room temperature resistivity is close to the Ioffe-Regel limit for a metal. Single crystal x-ray diffraction indicates a strong preference for Mn to occupy the larger pyramidal 3g site. The cation site preference in the as-grown crystals and the antiferromagnetism are not changed after high temperature anneals and a rapid quench to room temperature.