Metallic Behavior of Cyclotron Relaxation Time in Two-Dimensional Systems

TL;DR

This study investigates the cyclotron resonance relaxation time in high-mobility two-dimensional electron systems, revealing a metallic temperature dependence and a ratio exceeding unity near the metal-insulator transition.

Contribution

It provides new insights into the behavior of cyclotron relaxation time in 2D systems and its relation to the metal-insulator transition.

Findings

Relaxation time shows negative temperature dependence similar to dc resistivity.

The ratio of cyclotron to transport relaxation time exceeds unity near the transition.

The behavior suggests a link between cyclotron relaxation and metallic conduction.

Abstract

Cyclotron resonance of two-dimensional electrons is studied at low temperatures down to 0.4 K for a high-mobility Si/SiGe quantum well which exhibits a metallic temperature dependence of dc resistivity $\rho$. The relaxation time $\tau_{\rm CR}$ shows a negative temperature dependence, which is similar to that of the transport scattering time $\tau_t$ obtained from $\rho$. The ratio $\tau_{\rm CR}/\tau_t$ at 0.4 K increases as the electron density $N_s$ decreases, and exceeds unity when $N_s$ approaches the critical density for the metal-insulator transition.