Experimental study of weak antilocalization effects in a two-dimensional system: Anomalous dephasing rate

The quantum corrections to magnetoconductivity were studied in a high-mobility InGaAs/InAlAs sample with strong spin-orbit coupling. The weak antilocalization-induced drop in conductivity increases with decreasing conductivity. The experiment is well explained by theory. A spin-splitting energy larger than 5 meV obtained by fitting indicates strong spin-orbit coupling. The extracted dephasing rate as a function of temperature can be qualitatively described by modified Fermi-liquid theory with small-energy-transfer processes. Nonetheless, the extracted dephasing rate linearly increases with increasing conductivity, which is in conflict with the Fermi-liquid model.