CHINESE JOURNAL OF PHYSICS VOL. 39, NO. 4 AUGUST 2001

Spin-Dependent Transport in a Two-Dimensional GaAs Electron System

C.-T. Liang¹, Tsai-Yu Huang¹, Yu-Ming Cheng¹, Chao Han Pao¹, Chun-Cheng Lee¹, Gil-Ho Kim², and J. Y. Leem<sup>3

1</sup>Department of Physics, National Taiwan University, Taipei, Taiwan 106, R.O.C.

²Telecommunication Basic Research Laboratory, ETRI, Yusong P.O. Box 106, Taejon 305-600, Korea

³Materials Evaluation Centre, KRISS, P.O. Box 102, Taejon 305-600, Korea
(Received May 9, 2001)

We have measured the low-temperature electron transport properties in a front-gated GaAs/Al_0.33Ga_0.67As heterostructure. Collapse of spin-splitting and an enhanced Lande |g|-factor at both Landau level filling factors $\nu=3$ and $\nu=1$ were observed. Our experimental results show direct evidence that the electron-electron interactions are stronger at $\nu=3$ than those at $\nu=1$ over approximately the same perpendicular magnetic field range. Moreover, we observed an enhancement of the magnetoresistivity of a two-dimensional electron system with an increasing parallel magnetic field. Using a simple model, we suggest that the increase of the magnetoresistivity is due to spin but the model over-estimates the Lande |g| factor in our system.

PACS. 73.40.Gk - Tunneling.
PACS. 73.20.Dx - Electron states in low-dimensional structures.

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