Mechanism for the high Neel temperature in SrTcO_3

TL;DR

This paper investigates the microscopic reasons behind the high Neel temperature in SrTcO_3 using electronic structure calculations and Hubbard models, revealing the importance of d3 configuration and specific interaction parameters.

Contribution

It introduces a combined ab-initio and mean-field approach to explain the high Neel temperature in SrTcO_3, highlighting the role of d3 configuration and parameter space.

Findings

G-type antiferromagnetic state is robust across parameter space.

Large stabilization energies for small intraatomic exchange and large bandwidths.

The TN ratio of 4:1 matches experimental observations.

Abstract

The microscopic origin of the high Neel temperature (T_N) observed experimentally in SrTcO_3 has been examined using a combination of ab-initio electronic structure calculations and mean-field solutions of a multiband Hubbard model. The G-type antiferromagnetic state is found to be robust for a large region of parameter space, with large stabilization energies found, surprisingly, for small values of intraatomic exchange interaction strength as well as large bandwidths. The microscopic origin of this is traced to specific aspects associated with the d3 configuration at the transition-metal site. Considering values of interaction strengths appropriate for SrTcO3 and the corresponding 3d oxide SrMnO_3, we find a ratio of 4:1 for the TN as well as magnitudes consistent with experiment.