The Curie temperature and exchange energy between two sublattices in half-metallic greigite Fe3S4

TL;DR

This study investigates the magnetic properties of greigite (Fe3S4), determining its Curie temperature, exchange energy, and electronic structure, establishing its potential as a half-metallic material for spintronics.

Contribution

The paper provides the first comprehensive analysis of greigite's magnetic and electronic properties, linking experimental data with ab initio calculations to confirm its half-metallicity.

Findings

Curie temperature of greigite is about 677 K.

Exchange energy between sublattices is 3.25 meV.

Ueff = 1.16 eV predicts nearly perfect half-metallicity.

Abstract

High-temperature magnetic measurements have been carried out in hydrothermally synthesized greigite (Fe3S4). We show that the Curie temperature of greigite is significantly lower than that for its iron oxide counterpart Fe3O4. The lower TC value (about 677 K) of greigite is in quantitative agreement with that calculated using the exchange energy (3.25 meV) and the spin values of the two sublattices, which are inferred from the neutron and magnetization data of high-quality pure greigite samples. We further show that, with an effective on-site Hubbard energy Ueff = 1.16 eV, the lattice constant and two sublattice spins predicted from ab initio density-function theory are in nearly perfect agreement with the measured values. The parameter Ueff = 1.16 eV ensures Fe3S4 to be an excellent half-metallic material for spintronic applications.