MAGNETORESISTANCE OF A WEAKLY DISORDERED III-V SEMICONDUCTOR QUANTUM-WELL IN A MAGNETIC-FIELD PARALLEL TO INTERFACES

We have investigated the weak-localization effects on the magnetoresis tance of a two-dimensional electron gas in a quantum well of a semicon ductor with a zinc-blende crystal structure under a sufficiently weak magnetic field H applied parallel to interfaces, so it interacts only with the electron spins due to the Zeeman term in the Hamiltonian. We found a positive magnetoresistance, which depends strongly on the crys tal orientation of the well, and varies with the direction of the fiel d depending on the relative strengths of the Rashba and Dresselhaus te rms in the spin-orbit coupling. For a [001]-oriented well we found tha t the magnetic field destroys antilocalization when the Zeeman energy g mu H is larger than (tau(phi)tau(so))(-1/2), where tau(phi) is the i nelastic dephasing time and tau(so) the spin-orbit relaxation time. On the other hand, in a symmetric [011]-oriented quantum well, the Zeema n interaction leads to a weak localization of electrons.