Unusual Shubnikov-de Haas oscillations in BiTeCl

Abstract

We report measurements of Shubnikov-de Haas (SdH) oscillations in single crystals of BiTeCl at magnetic fields up to 31 T and at temperatures as low as 0.4 K. Two oscillation frequencies were resolved at the lowest temperatures, $F_1=65\pm 4$ Tesla and $F_2=156\pm 5$ Tesla. We also measured the infrared optical reflectance $\left(\mathcal{R}(\ddot{\mathcal{I}}‰)\right)$ and Hall effect; we propose that the two frequencies correspond respectively to the inner and outer Fermi sheets of the Rashba spin-split bulk conduction band. The bulk carrier concentration was $n_e\approx 1\times 10^{19}$ cm${}^{-3}$ and the effective masses $m_1^{\ast }=0.20m_0$ for the inner and $m_2^{\ast }=0.27m_0$ for the outer sheet. Surprisingly, despite its low effective mass, we found that the amplitude of $F_2$ is very rapidly suppressed with increasing temperature, being almost undetectable above $T\approx 4$ K.