Weak antilocalization and spin precession in quantum wells

The results of magnetoconductivity measurements in GaxIn1-xAs quantum wells are presented. The observed magnetoconductivity appears due to the quantum interference, which lead to the weak localization effect. It is established that the details of the weak localization are controlled by the spin splitting of electron spectra. A theory is developed that takes into account both linear and cubic in electron wave-vector terms in spin splitting, which arise due to the lack of inversion center in the crystal, as well as the linear terms that appear when the a;ell itself is asymmetric. It is established that, unlike spin-relaxation rate, contributions of different terms into magnetoconductivity are not additive. It is demonstrated that in the interval of electron densities under investigation [(0.98- 1.85) X 10(12) cm(-2)] all three contributions are comparable and have to be taken into account to achieve a good agreement between the theory and experiment. The results obtained from comparison of the experiment and the theory have allowed us to determine what mechanisms dominate the spin-relaxation in quantum wells and to improve the accuracy of determination of spin-splitting parameters in A(3)B(5) crystals and two-dimensional structures.