Quantum corrections to conductivity observed at intermediate magnetic fields in a high-mobility GaAs/AlxGa1-xAs two-dimensional electron gas

Magnetoresistance with the field perpendicular to the two-dimensional electron gas in a high-mobility GaAs/AlxGa1-xAs heterostructure at low temperatures is studied. At the lowest magnetic field we observe the weak localization. In particular we study the resistivity at magnetic fields, where the product of the mobility and the magnetic field is of the order of unity. The quantum correction to conductivity due to the electron-electron interaction [and other possible deviations from the free-electron (Drude) model], though having only a slight variation with magnetic field, nevertheless gives rise to a sizeable quadratic magnetoresistance in this regime. Our experiments yield in this way not only the well-known electron-electron term with the expected temperature dependence, but also a new type of temperature-independent quantum correction, which varies logarithmically with mobility.

© 1990 The American Physical Society