Spin-Orbit Scattering Time and Dephasing Time of Carriers in Two-Dimensional HgTe-CdTe Superlattices and Heterojunctions

摘要

Weak-localization studies of the two-dimensional electron gas in heterostructures made of HgTe adn CdTe are reported. Because of the small effective mass, the diffusion constant D is unusually large (824 sq. cm/s). By fitting the weak-field transverse magnetoresistance data from high-mobility samples (50,000 sq. cm/Vs, R = 720 ohms/unit area to the calculation of Hikami, Larkin, and Nagoka, we have determined the temperature (T) dependence of the spin-orbit scattering time and the dephasing time of carriers. The system is shown to have dominant spin-orbit scattering. (The spin-orbit rate is 0.6 times the elastic scattering rate.) The dephasing time which is linear in T agrees in magnitude with a calculation by Al-tshuler, Aronov, and Khmel'nitskii. Evidence for significant Coulomb interaction parameter derived from the plot of the resistance versus in T strongly disagrees with existing theories. Prominent anomalous magnetoresistance is also seen in the longitudinal geometry. The data are compared with the interaction theory (Zeeman splitting) and the weak-localization theory. Results from high-resistance (30 kilo ohm/unit area) samples which indicate the breakdown of perturbation theory are also reported.