Relationship between ferroelectricity and Dzyaloshinskii-Moriya interaction in multiferroics and the effect of bond-bending 

We studied the microscopic mechanism of multiferroics, in particular with the ”spin current” model (H. Katsura, N. Nagaosa and A. V. Balatsky, Phys. Rev. Lett. 95 , 057205 (2005)). Starting from a system with helical spin con- figuration, we solved for the forms of the electron wave functions and analyzed their characteristics. The relation between ferroelectricity and Dzyaloshinskii- Moriya interaction (I. Dzyaloshinskii, J. Phys. Chem. Solids 4 , 241 (1958) and T. Moriya, Phys. Rev. 120 , 91 (1960)) is clearly established. There is also a simple relation between the electric polarization and the wave vector of magnetic orders. Finally, we show that the bond-bending existing in transition metal oxides can enhance ferroelectricity. 

PACS: 75.80.+q, 77.80.-e 

Department of Physics and Center for Theoretical Sciences 

National Taiwan University 

C. D. Hu 

Taipei, Taiwan 

Republic of China 

## Abstract 

