Quantum magneto-transport in two-dimensional GaAs electron gases and SiGe hole gases
Journal
Journal of Physics and Chemistry of Solids
Journal Volume
62
Journal Issue
9-10
Pages
1789-1796
Date Issued
2001
Author(s)
Liang, C.-T.
Cheng, Y.-M.
Huang, T.Y.
Huang, C.F.
Simmons, M.Y.
Ritchie, D.A.
Kim, G.-H.
Leem, J.Y.
Chang, Y.H.
Abstract
We have measured the low-temperature transport properties of two-dimensional (2D) GaAs electron gases and 2D SiGe hole gases. Our experimental results fall into three categories. (i) Collapse of spin-splitting and an enhanced Landé g-factor at Landau level filling factors both ν = 3 and ν = 1 in a 2D GaAs electron gas are observed. Our experimental results show direct evidence that the effective disorder is stronger at ν = 1 than that at ν = 3 over approximately the same perpendicular magnetic field range. (ii) We present evidence for spin-polarisation of a dilute 2D GaAs electron gas. The Lande g-factor of the system is estimated to be 1.66. This enhanced g value is ascribed to electron-electron interactions at ultra low carrier density limit. (iii) In a high-quality SiGe hole gas, there is a temperature-independent point in the magnetoresistivity ρxx and ρxy which is ascribed to experimental evidence for a quantum phase transition between ν = 3 and ν = 5. We also present a study on the temperature(T)-driven flow lines in our system. © 2001 Elsevier Science Ltd. All rights reserved.
Type
journal article