The antiferromagnetic phase transition in the layered Cu$_{0.15}$Fe$_{0.85}$PS$_3$ semiconductor: experiment and DFT modelling

TL;DR

This study investigates the antiferromagnetic phase transition in Cu$_{0.15}$Fe$_{0.85}$PS$_3$ using experimental techniques and DFT modeling, revealing weak ferromagnetism and detailed spin interactions.

Contribution

It combines experimental M"{o}ssbauer spectroscopy and magnetic measurements with ab initio DFT simulations to analyze spin ordering and electronic structure in the layered alloy.

Findings

Evidence of weak ferromagnetism at low temperatures.

Calculated magnetic moments align with experimental data.

Insights into spin density contributions from Cu and S orbitals.

Abstract

The experimental studies of the paramagnetic-antiferromagnetic phase transition through M\"{o}ssbauer spectroscopy and measurements of temperature and field dependencies of magnetic susceptibility in the layered Cu$_{0.15}$Fe$_{0.85}$PS$_3$ crystal are presented. The peculiar behavior of the magnetization - field dependence at low-temperature region gives evidence of a weak ferromagnetism in the studied alloy. By the ab initio simulation of electronic and spin subsystems, in the framework of electron density functional theory, the peculiarities of spin ordering at low temperature as well as changes in interatomic interactions in the vicinity of the Cu substitutional atoms are analyzed. The calculated components of the electric field gradient tensor and asymmetry parameter for Fe ions are close to the ones found from M\"{o}ssbauer spectra values. The Mulliken populations show that the main contribution to the ferromagnetic spin density is originated from $3d$-copper and $3p$-sulfur orbitals. The estimated total magnetic moment of the unit cell (8.543~emu/mol) is in reasonable agreement with the measured experimental value of $\sim9$~emu/mol.