"Scaling of an anomalous metal/insulator transition in a 2D system in silicon at zero magnetic field"

Abstract

We have studied the temperature dependence of resistivity, $\rho$, for a two-dimensional electron system in silicon at low electron densities, $n_s\sim 10^{11}$ cm${}^{-2}$, near the metal/insulator transition. The resistivity was empirically found to scale with a single parameter, $T_0$, which approaches zero at some critical electron density, $n_c$, and increases as a power $T_0\propto |n_s-n_c{|}^{\beta }$ with $\beta =1.6\pm 0.1$ both in metallic ($n_s>n_c$) and insulating ($n_s<n_c$) regions. This dependence was found to be sample-independent. We have also studied the diagonal resistivity at Landau level filling factor $\nu =3/2$ where the system is known to be in a metallic state at high magnetic field and in an insulating state at low magnetic field. The temperature dependencies of resistivity at $B=0$ and at $\nu =3/2$ were found to be identical. These behaviors suggest a true metal/insulator transition in the two dimensional electron system in silicon at $B=0$, in contrast with the well-known scaling theory.

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