Electronic structure and magnetic interactions in strongly correlated transition-metal oxides

Abstract

Strongly correlated 3d-transition-metal oxides show a variety of interesting magnetic and electronic properties which make them potential candidates in the new field of spintronics. Due to strong on-site Coulomb-repulsions of 3d-electrons, density functional theory in local spin-density approximation (DFT–LSD) fails in giving an adequate electronic structure of these materials. Self-interacton corrected (SIC)–DFT–LSD strongly improves the description of such systems. Here we study the magnetic interactions in NiO and the NiO (100) surface in the framework of SIC–LSD. We extract exchange interaction constants of these systems by mapping total energies of different magnetic configurations onto a Heisenberg-Hamiltonian. Further we have investigated the effect of creating cation-vacancies in such systems. We find half-metallic behaviour for Mn_0.97O and Ni_0.97O. In particular, for NiO we find a half-metallic antiferromagnet which might have potential application in spintronics.

Keywords:

• Magnetism
• Strongly-correlated systems
• Half-metals
• Density functional theory

Acknowledgements

Support from the research group “Oxidic interfaces” and the ESF Psi-k Programme (STRUC) is gratefully acknowledged.

Notes

¹Textbook band theory predicts metallic behaviour in such a case.

²In the antiferromagnetic ordering of type 2 (AF2) planes of opposite spin are stacked in an alternating manner along the [111] direction.

³Ordering of type 1 (AF1) consists of planes of opposite spin stacked along the [100] direction. FM denotes ferromagnetic aligments.