Tilted Field Magnetotransport Experiments on Germanium Bicrystals
Previous magneto-transport experiments on p-type space charge layers adjacent to the grain boundary of Ge-bicrystals revealed the existence of a quantized, 2-dimensional system. Shubnikov-de Haas (SdH) experiments allowed the identification of two electric subbands, which can be attributed to light and heavy holes . The background magnetoresistance suggested that the g-factor of the holes should be much larger than 2. The determination of the g-factor of a 2D-system is sometimes possible by studying quantum oscillations in tilted magnetic fields . Because the Landau splitting depends on the normal component of the magnetic field and the spin splitting on the total field, the relative magnitude of the splittings varies with the tilt angle and gives rise to interference effects. These were actually observed in previous experiments , although no spin splitting of individual SdH peaks was found due to level broadening. Results of recent SdH- experiments in fields up to 23 T on high quality bicrystals produced in Würzburg are in good agreement with previous subband calculations . Again interference effects were found in tilted magnetic fields. They can be explained on the basis of numerical model calculations. The reason for the interference effects is that spin splitting, even if unresolved, gives rise to amplitude variations as a function of the tilt angle. The assigned g* factors of the light and heavy holes are considerably larger than 2, they are close to 6.
KeywordsTilt Angle Landau Level Heavy Hole Free Charge Carrier Spin Splitting
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