National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia.
Phys Rev Lett. 2013 Jun 21;110(25):257201. doi: 10.1103/PhysRevLett.110.257201. Epub 2013 Jun 17.
We have studied the magnetic field dependence of far-infrared active magnetic modes in a single ferroelectric domain BiFeO3 crystal at low temperature. The modes soften close to the critical field of 18.8 T along the [001] (pseudocubic) axis, where the cycloidal structure changes to the homogeneous canted antiferromagnetic state and a new strong mode with linear field dependence appears that persists at least up to 31 T. A microscopic model that includes two Dzyaloshinskii-Moriya interactions and easy-axis anisotropy describes closely both the zero-field spectroscopic modes as well as their splitting and evolution in a magnetic field. The good agreement of theory with experiment suggests that the proposed model provides the foundation for future technological applications of this multiferroic material.
我们研究了低温下单个铁电畴 BiFeO3 晶体中远红外活性磁模的磁场依赖性。这些模式在 [001] （赝立方）轴方向上沿着 18.8 T 的临界场软化，在此处，旋轨结构变为均匀倾斜反铁磁状态，并且出现了新的具有线性场依赖性的强模式，至少持续到 31 T。一个包含两个 Dzyaloshinskii-Moriya 相互作用和易轴各向异性的微观模型，紧密描述了零场光谱模式及其在磁场中的分裂和演化。理论与实验的良好一致性表明，所提出的模型为这种多铁材料的未来技术应用提供了基础。
