EXPERIMENTAL-DETERMINATION OF THE FERMI-SURFACE OF THIN SC1-XERXAS EPITAXIAL LAYERS IN PULSED MAGNETIC-FIELDS

High field magnetotransport measurements on thin Sc1-xErxAs layers bur ied in GaAs have been performed to obtain a detailed description of th e Sc1-xErxAs Fermi surface. The Shubnikov-de Haas (SdH) oscillations o bserved in the magnetoresistance and in the Hall effect are attributed to electron ellipsoids at the X points of the first Brillouin zone, a nd two hole spheres at the zone center. The masses of the charge carri ers are determined. The assignment of the SdH frequencies is confirmed by the analysis of the relative phases of the rho(xx) and the rho(yx) oscillations. A splitting of the SdH frequencies, due to the exchange interaction between the mobile charge carriers and the 4f Er spins, i s observed for the holes as well as for the electrons. Strong evidence is presented for confinement of the charge carriers in the Sc1-xErxAs quantum well. As a consequence of this confinement, the carrier densi ties decrease with decreasing thickness of the layers and the SdH osci llations show two-dimensional behavior.