g-factors of conduction electrons and holes in Bi2Se3 three-dimensional topological insulator

Bulk-related conduction electron spin resonance and conduction hole spin resonance were investigated in $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$, a three-dimensional topological insulator. Electrons in the conduction band and holes in the valence band both have spin \textonehalf{}. The effective $g$-factors for conduction electrons are equal to 27.3 \ifmmode\pm\else\textpm\fi{} 0.15 for magnetic field parallel to the c axis and 19.48 \ifmmode\pm\else\textpm\fi{} 0.07 for magnetic field perpendicular to the c axis, whereas for conduction holes 29.90 \ifmmode\pm\else\textpm\fi{} 0.09 for magnetic field parallel and 18.96 \ifmmode\pm\else\textpm\fi{} 0.04 for magnetic field perpendicular to the c axis, respectively. Nonparabolicity effects were not observed in the investigated low carrier concentration range, below $8\ifmmode\times\else\texttimes\fi{}{10}^{17}\phantom{\rule{0.28em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}3}$. Large $g$-factors, higher by an order of magnitude than the free electron value, are due to strong spin-orbit interactions in $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$. The striking similarity of the spin resonances due to conduction electrons and holes confirms the peculiar symmetry between the conduction and valence bands of $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$, both having similar effective masses and spin character.