Electrically induced decrease of magnetization in Ca3Mn2O7

The magnetoelectric effect of Ca3Mn2O7 is verified by measuring the electric field dependence of magnetization. The magnetization is reduced by the electric field, as much as nearly 6% at 4 K under 100 Oe magnetic field and 40 kV/m electric field. There are two theoretical models in previous researches. Harris's model [A. B. Harris, Phys. Rev. B 84, 064116 (2011)], based on the rotating effect of electric field predicts electric-field-direction dependence of the magnetization decrease. Benedek and Fennie's model [N. A. Benedek and C. J. Fennie, Phys. Rev. Lett. 106, 107204 (2011)] emphasizes the stretching effect of electric field and predicts direction independence. The experimental results support Benedek and Fennie's framework and conflict with Harris's prediction. We argue that the large anisotropy and the antiferromagnetic nature impede the rotation of domains and suppress the rotating effect. In the coupling of magnetic ordering and ferroelectric ordering, the oxygen octahedron tilt distortion (X3−) plays an essential role.