High-field Shubnikov–de Haas oscillations in the topological insulator Bi 2 Te 2 Se

We report measurements of the surface Shubnikov\char21{}de Haas oscillations (SdH) on crystals of the topological insulator Bi${}_{2}$Te${}_{2}$Se. In crystals with large bulk resistivity ($\ensuremath{\sim}4$ $\ensuremath{\Omega}\phantom{\rule{0.16em}{0ex}}$cm at 4 K), we observe $\ensuremath{\sim}15$ surface SdH oscillations (to the $n=1$ Landau level) in magnetic fields $B$ up to 45 T. Extrapolating to the limit $1/B\ensuremath{\rightarrow}0$, we confirm the $\frac{1}{2}$-shift expected from a Dirac spectrum. The results are consistent with a very small surface Land\'e $g$ factor.