Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan.
Phys Rev Lett. 2009 Dec 31;103(26):267206. doi: 10.1103/PhysRevLett.103.267206.
We have investigated the infrared optical Hall conductivity, sigma(xy)(omega) for band-filling-controlled ferromagnetic crystals of Nd2Mo2O7, revealing the dynamical properties of their anomalous Hall effect (AHE). A resonant structure and its systematic filling dependence were observed in the Hall conductivity spectra in the midinfrared region (typically at 0.1 eV), while similar effects were not discerned in the diagonal (longitudinal or ordinary) conductivity spectra. This property of sigma(xy)(omega) provides crucial and essential information to understand the microscopic mechanism of AHE including its dc limit. Specifically, the interband transition at the magnetic-monopole-like band-anticrossing point, which is split by spin chirality, is the dominant source in AHE.
我们研究了带填充控制的铁磁共振 Nd2Mo2O7 晶体的红外光学霍尔电导率σ(xy)(ω)，揭示了其反常霍尔效应(AHE)的动力学性质。在中红外区域(通常在 0.1eV 左右)观察到霍尔电导率谱中的共振结构及其系统填充依赖性，而在对角(纵向或普通)电导率谱中则没有观察到类似的效应。σ(xy)(ω)的这种性质为理解 AHE 的微观机制提供了关键和基本的信息，包括其直流极限。具体来说，由自旋手性分裂的磁单极带交叉点处的能带间跃迁是 AHE 的主要来源。
