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arXiv · 1507.01690

Optical properties of TlNi2Se2: Observation of pseudogap formation

X. B. Wang·H. P. Wang·Hangdong Wang·Minghu Fang·N. L. Wang
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Abstract

The quasi-two-dimensional nickel chalcogenides $TlNi_2Se_2$ is a newly discovered superconductor. We have performed optical spectroscopy study on $TlNi_2Se_2$ single crystals over a broad frequency range at various temperatures. The overall optical reflectance spectra are similar to those observed in its isostructure $BaNi_2As_2$. Both the suppression in $R(ω)$ and the peaklike feature in $σ_1(ω)$ suggest the progressive formation of a pseudogap feature in the midinfrared range with decreasing temperatures, which might be originated from the dynamic local fluctuation of charge-density-wave (CDW) instability. We propose that the CDW instability in $TlNi_2Se_2$ is driven by the saddle points mechanism, due to the existence of van Hove singularity very close to the Fermi energy.

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X. B. Wang, H. P. Wang, Hangdong Wang, Minghu Fang, N. L. Wang. 2015-12-28. Optical properties of TlNi2Se2: Observation of pseudogap formation. https://doi.org/10.1103/physrevb.92.245129

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