WARPED FERMI SURFACE IN GASB FROM SHUBNIKOV-DE HAAS MEASUREMENTS

The frequencies of Shubnikov-de Haas oscillations in n-type tellurium-doped GaSb have been obtained as a function of magnetic field direction in samples with electron concentrations n1018 cm-3. Field-modulation and phase-sensitive detection techniques were employed in the measurements. A frequency anisotropy of ∼1% has been unambiguously determined. These results are explained by the warping contribution to the k=0 conduction-band energy expression derived by Kane using k•p perturbation theory. By fitting the frequency anisotropy to the theoretical prediction, it is found that the warping parameter L-M-N=(11±2)22m0. A small (∼2%) effective-mass anisotropy has been observed; the symmetry of the result is predicted from the warping model, i.e., m*(111)>m*(110)>m*(100). © 1969 The American Physical Society.