Structure and spin dynamics of multiferroic BiFeO3

Abstract

Multiferroic materials have attracted much interest due to the unusual coexistence of ferroelectric and (anti-)ferromagnetic ground states in a single compound. They offer an exciting platform for new physics and potentially novel devices. BiFeO3 is one of the most celebrated of multiferroic materials with highly desirable properties. It is the only known room-temperature multiferroic with TC 1100 K and TN 650 K, and exhibits one of the largest spontaneous electric polarisation, P 80 μC/cm2. At the same time, it has a magnetic cycloid structure with an extremely long period of 630 Å, which arises from a competition between the usual symmetric exchange interaction and antisymmetric Dzyaloshinskii- Moriya (DM) interaction. There is also an intriguing interplay between the DM interaction and the single ion anisotropy K. In this review, we have tried to paint a complete picture of bulk BiFeO3 by summarising the structural and dynamical properties of both spin and lattice parts, and their magneto-electric coupling.