Metal-Insulator Transition atB=0in a Dilute Two Dimensional GaAs-AlGaAs Hole Gas

Abstract

We report the observation of a metal-insulator transition at $B=0\mathrm{}$ in a high mobility two dimensional hole gas in a GaAs-AlGaAs heterostructure. A clear critical point separates the insulating phase from the metallic phase, demonstrating the existence of a well defined minimum metallic conductivity ${\sigma }_{\min }{=2e}^2/h$. The $\sigma \left(T\right)$ data either side of the transition can be “scaled” onto one curve with a single parameter $T_0$. The application of a parallel magnetic field increases ${\sigma }_{\min }$ and broadens the transition. We argue that strong electron-electron interactions ( $r_s\simeq 10$) suppress quantum interference corrections to the conductivity.