Quantum versus semiclassical analysis of the conductivity of two-dimensional electrons in a magnetic field

Article

关键词: FERMION EFFECTIVE-MASS;    2-DIMENSIONAL ELECTRONS;    TRANSPORT-COEFFICIENTS;    COMPOSITE FERMIONS;    DELOCALIZED STATES;    LANDAU-LEVELS;    HALL REGIME;    ENHANCEMENT;    OSCILLATIONS;    LEVITATION;   

DOI  :  10.1103/PhysRevB.56.10446

来源: SCIE

【 摘 要 】

We present experimental evidence for the levitation of extended slates of a two-dimensional electron system in a magnetic field, and establish the presence of alternating regions of localized and extended states in the density of states to Landau-level filling factors (nu) as high as 80. Monitoring the Hall voltage of a modulation-doped GaAs/AlxGa1-xAs heterojunction at fixed magnetic field during continuous illumination from light-emitting diodes reveals a steplike structure with plateaus at even integer nu between 22 and 80 at a temperature of 0.3 K. We derive a general expression for the conductivity due to rectangular bands of extended states, and show that the observed temperature dependence of the Shubnikov-de Haas oscillations is consistent with this picture. An analysis of the oscillations using this expression reveals the predicted levitation of the extended states.

【 授权许可】

Free