Electronic correlation effects in the Cr2GeC Mn+1AXn phase

TL;DR

This study investigates the electronic and magnetic properties of Cr2GeC using advanced computational methods, revealing a compensated antiferromagnetic ground state and emphasizing the importance of electron correlation effects in understanding its behavior.

Contribution

The paper provides a detailed analysis of Cr2GeC's electronic structure using GGA+U, highlighting the role of strong electron correlations and identifying the magnetic ground state.

Findings

Cr2GeC has a compensated antiferromagnetic ground state.

Structural properties agree with experimental data.

Fermi surface analysis shows asymmetrical carrier distribution.

Abstract

The magnetic properties, electronic band structure and Fermi surfaces of the hexagonal Cr2GeC system have been studied by means of both generalized gradient approximation (GGA) and the +U corrected method (GGA+U). The effective U value has been computed within the augmented plane-wave theoretical scheme by following the constrained density functional theory formalism of Anisimov et al. [1991 Phys. Rev. B 45, 7570]. On the basis of our GGA+U calculations, a compensated anti-ferromagnetic spin ordering of Cr atoms has been found to be the ground state solution for this material, where a Ge-mediated super-exchange coupling is responsible for an opposite spin distribution between the ABA stacked in-plane Cr-C networks. Structural properties have also been tested and found to be in good agreement with the available experimental data. Topological analysis of Fermi surfaces have been used to qualitatively address the electronic transport properties of Cr2GeC and found an important asymmetrical carrier-type distribution within the hexagonal crystal lattice. We conclude that an appropriate description of the strongly correlated Cr-d electrons is an essential issue for interpreting the material properties of this unusual Cr-based MAX-phase.