Scaling of the magnetoconductivity of silicon MOSFET's: evidence for a quantum phase transition in two dimensions

Abstract

For a broad range of electron densities $n$ and temperatures $T$, the in-plane magnetoconductivity of the two-dimensional system of electrons in silicon MOSFET's can be scaled onto a universal curve with a single parameter $H_σ(n,T)$, where $H_σ$ obeys the empirical relation $H_σ=A (n) [Δ(n)^2 +T^2]^{1/2}$. The characteristic energy $k_B Δ$ associated with the magnetic field dependence of the conductivity decreases with decreasing density, and extrapolates to 0 at a critical density $n_0$, signaling the approach to a zero-temperature quantum phase transition. We show that $H_σ=AT$ for densities near $n_0$.