Dimensional control of antilocalization and spin relaxation in quantum wires

The weak localization correction to the conductivity of quantum wires with linear Rashba-Dresselhaus spin-orbit coupling is derived analytically as function of wire width W. The spin relaxation rate is found to decrease as W becomes smaller than the spin-precession length L-SO. As a result, the sign of the conductivity correction switches to weak localization, positive magnetoconductivity for wire widths smaller than L-SO. A relaxation rate due to the cubic Dresselhaus coupling gamma with a corresponding length scale L-gamma remains, however, even in narrow wires W << L-SO. At low temperature, an antilocalization peak with negative magnetoconductivity is therefore recovered when the dephasing length exceeds L-gamma.