S. G. Semenchinskii, L. Smrcka, P. Vasek
Journal of Experimental and Theoretical Physics Letters
At electron densities NS>6×10−2 cm−22 a second series of oscillations, which are tentatively attributed to population of the second energy subband, is observed in addition to the main series of Shubnikov-de Haas oscillations. A change in phase of the oscillations of the second series is observed at some angle of inclination αe of the field. The measured value of αe is used to calculate the ratio of the cyclotron mass to the effective g factor. The maximum possible cyclotron mass is also determined as mH< 0.32me. On this basis it is concluded that the second series of oscillations is due to electrons which have an in-plane effective mass m*≈0.2me and which belong to the same valleys of the Fermi surface as in the case of the main oscillations.