Temperature dependence of the amplitude of the Shubnikov-De Haas oscillations in a two-dimensional gas

Shubnikov-de Haas measurements have been performed on a high-mobility AlxGa1-xAs/GaAs heterostructure as a function of temperature (1.7T4.2 K) and magnetic field strength (0.25 B0.70T). The temperature dependence of the amplitude of the Shubnikov-de Haas oscillations is used to define an effective mass of the two-dimensional electron gas. This apparent mass depends strongly on temperature and magnetic field and decreases to values much smaller than that for the cyclotron mass. The apparent mass shows a scaling behavior as a function of the dimensionless quantit