At present we are concentrating on the four topics below,

1. Spin-dependent transport in a dilute 2D GaAs electron gas

In this work we investigate spin-dependent transport in a parallel magnetic field. In the dilute electron density limit, we show evidence for spin polarisation in an in-plane magnetic field. Using a simple model, we estimate the Land\e g-factor in this dilute 2DEG to be about 3.32. This enhanced Lande g-factor compared with that of a bulk GaAs 2D electron system (0.44) is ascribed to electron-electron interaction effects at ultra-low electron densities and the fact that over the whole measurement range r_s does not vary significantly.

2. Spin-dependent transport in a quasiballistic quantum wire

In this work we describe the transport properties of a 5 mm long one-dimensional (1D) quantum wire. Reduction of conductance plateaux due to the introduction of weakly disorder scattering are observed. In an in-plane magnetic field, we observe spin-splitting of the reduced conductance steps. Our experimental results provide evidence that deviation from conductance quantisation is very small for electrons with spin parallel and is about 1/3 for electrons with spin anti-parallel. Moreover, in a high in-plane magnetic field, a spin-polarised 1D channel shows a plateau-like structure close to 0.3 ×2e²/h which strengthens with em increasing temperatures. It is suggested that these results arise from the combination of disorder and the electron-electron interactions in the 1D electron gas. [Please see C.-T. Liang et al., Phys. Rev. B 61, 9952 (2000) for details.]

3. Temperature-driven flow lines and phase transitions in a SiGe hole gas

We present the first study of temperature-driven flow lines in the “anomalous Hall insulator" regime near a Landau level filling factor n =1.5. The “anomalous"temperature-driven flow lines could be due to the unusual energy level scheme in a Si/SiGe hole system. Moreover, for 3< n <5, there is a temperature-independent point in s_xx(B), s_xy(B), r_xx(B) and r_xy(B) which corresponds to a boundary of the quantum phase transition. [Please see C.-T. Liang et al., Chin. J. Phys. 39, L305 (2001) for details.

4. Evidence of collapse of spin-splitting in the quantum Hall regime

In this work, we observe evidence for collapse of spin-splitting and an enhanced Lande g-factor at Landau level filling factors both n=3 and n=1 in a 2D GaAs electron gas are observed. Our experimental results show direct evidence that the effective disorder is stronger at n=1 than that at n=3 over approximately the same perpendicular magnetic field range.[Please see C.-T. Liang et al., J. Chem. Phys. Sol. 62, 1789 (2001) for details.]

Corrections, comments to:
Tse-Ming Chen