SCALING OF AN ANOMALOUS METAL-INSULATOR-TRANSITION IN A 2-DIMENSIONAL SYSTEM IN SILICON AT B=O

We have studied the temperature dependence of resistivity, , for a two-dimensional electron system in silicon at low electron densities ns1011 cm-2, near the metal-insulator transition. The resistivity was empirically found to scale with a single parameter T0, which approaches zero at some critical electron density nc and increases as a power T0ns-nc with =1.60.1 both in metallic (ns>nc) and insulating (ns<nc) regions. This dependence was found to be sample independent. We have also studied the diagonal resistivity at Landau-level filling factor =3/2, where the system is known to be in a true metallic state at high magnetic field and in an insulating state at low magnetic field. The temperature dependencies of resistivity at B=0 and =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. © 1995 The American Physical Society.