Temperature-dependent excitonic superuid plasma frequency evolution in an excitonic insulator, Ta2NiSe5
SCIE
SCOPUS
- Title
- Temperature-dependent excitonic superuid plasma frequency evolution in an excitonic insulator, Ta2NiSe5
- Authors
- Seo, Yu-Seong; Eom, Man Jin; Kim, Jun Sung; Kang, Chang-Jong; Min, Byung Il; Hwang, Jungseek
- Date Issued
- 2018-08
- Publisher
- Nature Publishing Group
- Abstract
- An interesting van der Waals material, Ta2NiSe5 has been known one of strong excitonic insulator candidates since it has very small or zero bandgap and can have a strong exciton binding energy because of its quasi-one-dimensional crystal structure. Here we investigate a single crystal Ta2NiSe5 using optical spectroscopy. Ta2NiSe5 has quasi-one-dimensional chains along the alpha-axis. We have obtained anisotropic optical properties of a single crystal Ta2NiSe5 along the alpha-and c-axes. The measured alpha- and c-axis optical conductivities exhibit large anisotropic electronic and phononic properties. With regard to the alpha-axis optical conductivity, a sharp peak near 3050 cm(-1) at 9 K, with a well-defined optical gap ((EI)(OP) similar or equal to 1800 cm(-1)) and a strong temperature-dependence, is observed. With an increase in temperature, this peak broadens and the optical energy gap closes around similar to 325 K (T-C(EI)). The spectral weight redistribution with respect to the frequency and temperature indicates that the normalized optical energy gap (((EI)(OP)(T)/(EI)(OP)(o)))is 1 - (T/T-C(EI))(2). The temperature-dependent superfluid plasma frequency of the excitonic condensation in Ta2NiSe5 has been determined from measured optical data. Our study may pave new avenues in the future research on excitonic insulators.
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/95710
- DOI
- 10.1038/s41598-018-30430-9
- ISSN
- 2045-2322
- Article Type
- Article
- Citation
- Scientific Reports, vol. 8, no. 1, 2018-08
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