Sealing behavior and universality near the quantum Hall transition

Article

关键词: 2-DIMENSIONAL ELECTRON-SYSTEM;    STRONG MAGNETIC-FIELD;    LOWEST LANDAU-LEVEL;    INSULATOR-TRANSITION;    LOCALIZATION LENGTH;    2 DIMENSIONS;    ISING-MODEL;    PERCOLATION;    STATES;    LATTICE;   

DOI  :  10.1103/PhysRevB.55.10661

来源: SCIE

【 摘 要 】

A two-dimensional lattice system of noninteracting electrons in a homogeneous magnetic field with half a flux quantum per plaquette and a random potential is considered. For the large-scale behavior a supersymmet ric theory with collective fields is constructed and studied within saddle-point approximation and fluctuations. The modelis characterized by a broken supersymmetry indicating that only the fermion collective field becomes delocaIized whereas the boson field is exponentially localized. Power counting for the Auctuation terms suggests that the interactions between delocalized Auctuations are irrelevant. Several quasiscaling regimes, separated by large crossover lengths, are found with effective exponents v for the localization length xi(l). In the asymptotic regime there is v = 1/2 in agreement with an earlier calculation of Affleck and one by Ludwig et al. for a finite density of states. The effective exponent, relevant for physical system, is v = 1 where the coefficient of xi(l) is growing with randomness. This is in agreement with recent high-precision measurements on Si metal-oxide-semiconductor field-effect transistor, and AlxGa1-xAs/GaAs samples.

【 授权许可】

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