Anomalous Shubnikov-de Haas oscillations in two-dimensional systems

Shubnikov-de Haas (SdH) oscillations have long been used to measure the une qual spin-subband densities of inversion asymmetric two-dimensional (2D) sy stems. Our experiments and self-consistent numerical calculations for 2D Ga As hole systems indicate that, in general, these oscillations are not simpl y related to the population of spin-split subbands at zero-magnetic-field T he SdH oscillations depend sensitively on the crystallographic growth direc tions of a semiconductor quantum well. Our quantum mechanical analysis reve als the inapplicability of conventional Bohr-Sommerfeld quantization for sy stems with spin-orbit interaction. (C) 2001 Elsevier Science B.V. All right s reserved.