Katsura Hosho, Balatsky Alexander V, Nagaosa Naoto
Department of Applied Physics, the University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Phys Rev Lett. 2007 Jan 12;98(2):027203. doi: 10.1103/PhysRevLett.98.027203. Epub 2007 Jan 11.
We develop a theory of collective mode dynamics in the helical magnets coupled to electric polarization via spin-orbit interaction. The low-lying modes associated with the ferroelectricity are not the transverse optical phonons, but are the spin waves hybridized with the electric polarization. This hybridization leads to the Drude-like dielectric function epsilon(omega) in the limit of zero magnetic anisotropy. There are two additional low-lying modes: phason of the spiral and rotation of helical plane along the polarization axis. Role of these low-lying modes in the neutron scattering and antiferromagnetic resonance is revealed, and a novel experiment to detect the dynamical magnetoelectric coupling is discussed.
我们发展了一种关于通过自旋轨道相互作用与电极化耦合的螺旋磁体中集体模式动力学的理论。与铁电相关的低能模式不是横向光学声子，而是与电极化杂化的自旋波。这种杂化在零磁各向异性极限下导致了类似德鲁德的介电函数ε(ω)。还有另外两种低能模式：螺旋的相子和螺旋平面沿极化轴的旋转。揭示了这些低能模式在中子散射和反铁磁共振中的作用，并讨论了一种检测动态磁电耦合的新实验。
