Optical study of charge instability in CeRu2Al10 in comparison with CeOs2Al10 and CeFe2Al10

概要

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The anisotropic electronic structure responsible for the antiferromagnetic transition in CeRu2Al10 at the unusually high temperature of T0=28 K was studied using optical conductivity spectra, Ce 3d x-ray photoemission spectra, and band calculation. It was found that the electronic structure in the ac plane is that of a Kondo semiconductor, whereas that along the b axis has a nesting below 32 K (slightly higher than T0). These characteristics are the same as those of CeOs2Al10 [ S. Kimura et al. Phys. Rev. Lett. 106 056404 (2011)]. The c-f hybridization intensities between the conduction and 4f electrons of CeRu2Al10 and CeOs2Al10 are weaker than that of CeFe2Al10, showing no magnetic ordering. These results suggest that the electronic structure with one-dimensional weak c-f hybridization along the b axis combined with two-dimensional strong hybridization in the ac plane causes charge-density wave (CDW) instability, and the CDW state then induces magnetic ordering.