Ab-initio Study on the Magnetic Structures in the Ordered Mn3Pt Alloy

TL;DR

This study uses density functional theory to analyze the magnetic structures of Mn3Pt alloy, challenging previous assumptions about its magnetic moments and suggesting thermal fluctuations instead of paramagnetism in the F-phase.

Contribution

The paper provides a first-principles analysis showing the unlikelihood of the previously assumed magnetic configuration in Mn3Pt's F-phase.

Findings

The assumed non-magnetic Mn atoms in the F-phase are energetically unfavorable.

The magnetic moments on one-third of Mn atoms are likely thermally fluctuating.

Results align with recent neutron scattering observations.

Abstract

We study the electronic states of the magnetically ordered Mn3Pt alloy within the density functional theory. Mn3Pt has been believed that one third of Mn atoms have no magnetic moment in an antiferromagnetic phase (so-called the F-phase) realized in the temperature range of 400 K < T < 475 K. We show that this experimentally suggested spin configuration is energetically so much unfavorable that it would be irrelevant to the F-phase. We discuss the possibility that the spin moments on the one third of Mn atoms are not paramagnetic but thermally fluctuating in the F-phase. The present results have an immediate connection with the recent neutron scattering study [T. Ikeda and Y. Tsunoda, J. Phys. Soc. Jpn., vol. 72, pp. 2614-2621, October. 2003.].