Onset of Magnetic Order in Strongly-Correlated Systems from ab initio Electronic Structure Calculations: Application to Transition Metal Oxides

TL;DR

This paper presents an ab initio method combining spin density functional theory and a disordered local moment approach to predict magnetic ordering in strongly-correlated transition metal oxides at finite temperatures.

Contribution

It introduces a self-interaction corrected local spin density functional within the KKR method for finite temperature magnetism without fitting to effective models.

Findings

Reproduces experimental magnetic ordering tendencies

Qualitative trend in ordering temperatures captured

Large insulating gap persists across magnetic transition

Abstract

We describe an ab initio theory of finite temperature magnetism in strongly-correlated electron systems. The formalism is based on spin density functional theory, with a self-interaction corrected local spin density approximation (SIC-LSDA). The self-interaction correction is implemented locally, within the KKR multiple-scattering method. Thermally induced magnetic fluctuations are treated using a mean-field `disordered local moment' (DLM) approach and at no stage is there a fitting to an effective Heisenberg model. We apply the theory to the 3d transition metal oxides, where our calculations reproduce the experimental ordering tendencies, as well as the qualitative trend in ordering temperatures. We find a large insulating gap in the paramagnetic state which hardly changes with the onset of magnetic order.