Effect of Spin-Orbit Scattering on the Mesoscopic Conductance Fluctuation Amplitude in GaAs/AlGaAs Heterojunctions

Abstract

Universal conductance fluctuations (UCF) are a novel quantum interference effect in small, weakly random systems which cleanly demonstrate the importance of electron phase coherence at low temperatures (Lee, Stone, and Fukuyama, 1987). Recently, much attention in the study of UCF has been focused on the effects of magnetic field and spin-orbit (SO) scattering on the rms fluctuation amplitude δG. The interest in this aspect was largely stimulated by the use of random-matrix theories (RMT) to describe quantum transport (Altshuler and Shklovskii, 1986; Imry, 1986; Muttalib et al., 1987; Mello, 1988). These theories predict the relative size of δG in different regimes based on general symmetry properties of the system under study; thus δG is independent of the microscopic details of the system. For example, the breaking of time-reversal symmetry by an external magnetic field or of spin-rotation symmetry by SO scattering produces an experimentally observable change in δG. Diagrammatic theories (Lee et al., 1987; Stone, 1989; Feng, 1989) predict the same changes in δG, although the symmetry properties do not appear as explicitly. These changes are summarized in the table below.