Zero-field spin splitting and spin-dependent broadening in high-mobility InSb/In1-xAlxSb asymmetric quantum well heterostructures

We present high-field magnetotransport data from a range of 30-nm-wide InSb/InAlSb quantum wells with room-temperature mobilities in excess of 6 m2 V−1 s−1. Samples with the narrowest Landau level broadening exhibit beating patterns in the magnetoresistance attributed to zero-field spin splitting. Rashba parameters are extracted from a range of samples and gate biases using the difference in spin populations inferred from fast Fourier transforms of the data. The influence of Landau level broadening and spin-dependent scattering rates are investigated by magnetoconductance simulations, which provide key signatures that we were able to verify by experimental observation. These results demonstrate that in addition to the large Zeeman splitting, the combination of large and spin-dependent broadening is the significant parameter in controlling the appearance of beating in these structure