Anisotropic optical conductivity of the putative Kondo insulator CeRu4Sn6
Anisotropic optical conductivity of the putative Kondo insulator CeRu4Sn6
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DOI：
10.1103/physrevb.87.115129
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发表时间：
2013-03-21
影响因子：
3.7
通讯作者：
Paschen, S.
中科院分区：
文献类型：
--
作者：
Guritanu, V.;Wissgott, P.;Paschen, S.
近藤绝缘体，尤其是它们的非立方体绝缘体一直知之甚少。在这里，我们报道了在宽的频率和温度范围内利用光学反射率测量在四方化合物CeRu4Sn6中产生的各向异性的能量伪隙。低能光学导电性在a-a面内表现出类似半导体的特征，但在c轴上表现出类似Drude的响应，表明金属弱。局域密度近似加上动力学平均场理论计算定性地再现了这些观测结果，并有助于确定它们的起源。对于布里渊区的大部分区域，强关联能带结构在近藤共振中呈现出一个很窄的直接带隙。只有在c方向，由于杂化的各向异性，在费米能级上有一个明显的带交叉。DOI：10.1103/PhysRevB.87.115129
Kondo insulators and in particular their noncubic representatives have remained poorly understood. Here we report on the development of an anisotropic energy pseudogap in the tetragonal compound CeRu4Sn6 employing optical reflectivity measurements in broad frequency and temperature ranges. The low-energy optical conductivity shows semiconductor-like features within the a-a plane but a Drude-like response along the c axis, signaling weak metallicity. Local density approximation plus dynamical mean-field theory calculations reproduce these observations qualitatively and help to identify their origin. For large parts of the Brillouin zone, the strongly correlated band structure presents a narrow direct gap within the Kondo resonance. Only for the c direction, due to anisotropy in the hybridization, there is a pronounced band crossing at the Fermi level. DOI: 10.1103/PhysRevB.87.115129