Abstract | In recent years, we have theoretically studied the microscopic origin of ferroelectricity in different multiferroic systems. We proposed a unified model [1,2] which includes purely electronic and ion-displacement contributionsimultaneously to describe spin-order induced ferroelectricity. An efficient method [3] was developed to compute the model parameters from first-principles. On the basis of the unified model and density functional calculations, we explained the ferroelectricity induced by the proper-screw spin spiral [2], discovered a novel magnetoelectric coupling mechanism in which the magnitude of the polarization is governed by the exchange striction with the direction by the spin chirality [4], proposed that the ferroelectricity in the chiral-lattice magnet Cu2OSeO3 is due to the unusual single-spin site term [5], unraveled that the magnetoelectric effect observed in BiFeO3 originates from the exchange striction [2]. References 1. H. J. Xiang, E. J. Kan, Y. Zhang, M.-H. Whangbo, and X. G. Gong, Phys. Rev. Lett.107, 157202 (2011). 2. H. J. Xiang, P. S. Wang, M.-H. Whangbo, and X. G. Gong, Phys. Rev. B 88, 054404 (2013). 3. H. J. Xiang, E. J. Kan, Su-Huai Wei, M.-H. Whangbo, and X. G. Gong, Phys. Rev. B 84, 224429 (2011). 4. X. Z. Lu, M.-H. Whangbo, Shuai Dong, X. G. Gong, and H. J. Xiang, Phys. Rev. Lett.108, 187204 (2012). 5. J. H. Yang, Z. L. Li, X. Z. Lu, M.-H. Whangbo, Su-Huai Wei, X. G. Gong, and H. J. Xiang, Phys. Rev. Lett.109, 107203 (2012). |
