JPS Conf. Proc. 30, 011017 (2020) [5 pages]
Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2019)
Magneto-Optics of the Weyl Semimetal TaAs in the THz and IR Regions
1Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan
2Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
3Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
Received August 23, 2019

The magnetic-field dependence of optical reflectivity [\(R(\omega )\)] and optical conductivity [\(\sigma (\omega )\)] spectra of the ideal type-I Weyl semimetal TaAs has been investigated at the temperature of 10 K in the terahertz (THz) and infrared (IR) regions. The obtained \(\sigma (\omega )\) spectrum in the THz region of \(\hbar \omega \leq 15\) meV is strongly affected by the applied magnetic field (B): The Drude spectral weight is rapidly suppressed and an energy gap originating from the optical transition in the lowest Landau levels appears with a gap size that increases in proportion to \(\sqrt{B} \), which suggests linear band dispersions. The obtained THz \(\sigma (\omega )\) spectra could be scaled not only in the energy scale by \(\sqrt{B} \) but also in the intensity by \(1/\sqrt{B} \) as predicted theoretically. In the IR region for \(\hbar \omega \geq 17\) meV, on the other hand, the observed \(R(\omega )\) peaks originating from the optical transitions in higher Landau levels are proportional to linear-B suggesting parabolic bands. The different band dispersions originate from the crossover from the Dirac to the free-electron bands.

©2020 The Author(s)
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