Shubnikov-de Haas effect of the quasi-two-dimensional electron system in InSb grain boundaries in tilted magnetic fields

Abstract

The Shubnikov-de Haas effect and the Hall effect of a quasi-two-dimensional inversion layer adjacent to the grain boundary in an InSb bicrystal are investigated in magnetic fields up to 9 T at various angles from 0 degrees to 90 degrees between the grain boundary plane normal vector and the field direction at a temperature of 1.5 K. Whereas the Hall effect and the oscillations of the magnetoresistance of the ground electric subband are due to the perpendicular magnetic field component only, the SDH oscillations of the first excited subband show remarkable deviations from the ideal two-dimensional behaviour. The experimental results yield a nonvanishing dispersion relation perpendicular to the interface, which is shown to be possibly due to the spatial extension of the wavefunction of the first subband. Observations of the diamagnetic Shubnikov-de Haas effect show good agreement with theoretical predictions and confirm calculations indicating that four subbands are occupied in the system.