Electronic structure and magnetic and optical properties of double perovskite Bi2FeCrO6 from first-principles investigation

TL;DR

This study uses advanced first-principles calculations to reveal that Bi2FeCrO6 is a ferrimagnetic semiconductor with a high Curie temperature, providing insights into its electronic, magnetic, and optical properties for potential applications.

Contribution

The paper presents a comprehensive first-principles investigation of Bi2FeCrO6, showing it is a stable ferrimagnetic semiconductor with a high Curie temperature, surpassing previous DFT results.

Findings

Bi2FeCrO6 is a robust ferrimagnetic semiconductor.

The magnetic Curie temperature is calculated as 450 K.

The main magnetic interaction is antiferromagnetic superexchange between Fe and Cr.

Abstract

Double perovskite Bi$_2$FeCrO$_6$, related with BiFeO$_3$, is very interesting because strong ferroelectricity and high magnetic Curie temperature beyond room temperature are observed in it. However, existing density-functional-theory (DFT) studies, using pseudo-potentials, produce metallic ground state under the local density approximation (LDA) and need LDA+U method to yield needed nonmetallic ground state, resulting in low magnetic Curie temperature (below 130 K). Here, we optimize its crystal structure and then investigate its electronic structure and magnetic and optical properties by combining the full-potential augmented plane wave method with Monte Carlo simulation. Our optimized structure is a robust ferrimagnetic semiconductor. This nonmetallic phase is formed due to crystal field splitting and spin exchange splitting, in contrast to Mott-Hubbard states in previous DFT studies. Spin exchange constants and optical properties are calculated. Our ab initio magnetic Curie temperature is 450 K, much higher than previous DFT-based value and consistent with experimental results. Our study and analysis reveals that the main magnetic mechanism is an antiferromagnetic superexchange between Fe and Cr over the intermediate O atom. These results are useful to understanding such perovskite materials and exploring their potential applications.