Electronic structure, magnetism and optical properties of orthorhombic GdFeO3 from first principles

Abstract

Orthorhombic GdFeO₃ has attracted considerable attention in recent years because its magnetic structure is similar to that of the well-known BiFeO₃ material. Here, we investigate the electronic structure, magnetism and optical properties of orthorhombic GdFeO₃ in terms of density-functional-theory calculations. The modified Becke-Johnson (mBJ) exchange potential is adopted to improve on the description of the electronic structure. Our calculations show that the G-type antiferromagnetic (G-AFM ordering of Fe spins) phase of orthorhombic GdFeO₃ is stable compared to other magnetic phases. The semiconductor gap calculated with mBJ, substantially larger than that with GGA, is in good agreement with recent experimental values. Additionally, we also investigate the effects of spin–orbit coupling on the electronic structure, and calculate the complex dielectric functions and other optical functions of photon energy. The magnetic exchange interactions are also investigated, which gives a Néel temperature close to experimental observation. For confirming these mBJ results, we also study the electronic structure of rhombohedral (R3c) BiFeO₃ with mBJ, obtaining good consistency with experiment. These lead to a satisfactory theoretical understanding of the electronic structure, magnetism and optical properties of orthorhombic GdFeO₃ and can help elucidate the electronic structures and optical properties of other similar materials.