Scaling of an anomalous metal-insulator transition in a two-dimensional system in silicon atB=0

Abstract

We have studied the temperature dependence of resistivity, p, for a two-dimensional electron system in silicon at low electron densities n, 10 cm, near the metal-insulator transition. The resistivity was empirically found to scale with a single parameter Tp, which approaches zero at some critical electron density n, and increases as a power To oc~n,n,~with P = 1.6 6 0.1 both in metallic (n,) n,) and insulating (n, (n) regions. This dependence was found to be sample independent. We have also studied the diagonal resistivity at Landau-level filling factor v =-,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 at v =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.

Singular or non-Fermi liquids

“…• Near r s = r sc , the resistivity as a function of temperature on the insulating side appears to be a re ection of that on the metallic side about the d =dT = 0 line if the data is not considered at low temperatures [149]. Now with more complete data, we know that the resistivity attens to zero slope at low temperatures on the "metallic" side of n c .…”

“…Despite the accumulated theoretical and empirical wisdom acquired over all these years, the experimental observation made in 1995 of a metal-insulator transition in two dimensions [149] was a major surprise and is a subject of great current controversy. The theoretical work in the 1980s [11,[92][93][94]157,14] on disordered interacting electrons pointed to a major unsolved theoretical problem in two dimensions.…”

Magnetic-field-induced superconductor–metal-insulator transitions in bismuth metal graphite

“…1 In high-mobility Si metal oxide-semiconductor field-effect transistor (MOSFET), the in-plane resistivity for a system with an electron density n larger than a critical electron density n c decreases with decreasing T , indicating a metallic behavior. 2,3,4 This metallic state is completely destroyed by the application of an external magnetic field (H) applied in the basal plane when H is higher than a threshold field H c . Such coplanar fields only polarize the spins of the electrons, indicating that the spin state is significant to the high conductivity of the metallic state.…”

Metal-insulator transition in amorphousSi1−xNix:Evidence for Mott’s minimum metallic conductivity

“…The recent discovery of a sharp MIT in two-dimensional disordered systems [23][24][25][26] has drawn interest to this subject, too. The scaling theory of localization of non-interacting electrons [3] states that two-dimensional systems exhibit principally only activated conduction, and denies the existence of an MIT in this situation.…”