Landau transitions at higher gaps in InSb and GaSb

Landau levels have been resolved at the E₁ + Δ₁ gap in InSb and at the E₁ edge in GaSb. Transverse reduced masses of 19 ± 3 and 21.4 ± 1.5 have been obtained at the respective edges. Using band gaps determined from the experiment, the spin-orbit splitting Δ₁ has been measured as 0.500 ± 0.013 eV in InSb. Combined with a measurement of the zone center spin-orbit splitting, this gives a ratio of 0.623 ± 0.02 of slightly less than $\text{2}\text{3}$.