Spin-lattice coupling and helical-spin driven ferroelectric polarization in multiferroic CuFeO2

Abstract

Based on density functional theory, we elucidate the origin of ferroelectricity of multiferroic CuFeO2 with collinear and noncollinear magnetic structure calculations. By comparing the lattice geometry and electronic structures of different magnetic orderings, we confirm that the up-up-down-down spin arrangement plays an important role in the formation of band gap, the decrease in total energy, and the increase in magnetic moment. However, the system of CuFeO2 undergoes a large lattice distortion due to helical-spin ordering. In particular, the strong hybridizations of Fe 3d with O 2p states drive ferroelectric polarization, which provides a first-principle understanding of multiferroicity in CuFeO2. © 2010 American Institute of Physics.