The energy scale behind the metallic behaviors in low-density Si-MOSFETs

Abstract

We show that the unexpected metallic behavior (the so-called two-dimensional metal-insulator transition) observed in low-density Silicon metal-oxide-semiconductor field-effect transistors (Si-MOSFETs) is controlled by a unique characteristic energy scale, the polarization energy. On one hand, we perform Quantum Monte Carlo calculations of the energy needed to polarize the two dimensional electron gas at zero temperature, taking into account Coulomb interactions, valley degeneracy and electronic mobility (disorder). On the other hand, we identify the characteristic energy scale controlling the physics in eight different sets of experiments. We find that our {\it ab-initio} polarization energies (obtained without any adjustable parameters) are in perfect agreement with the observed characteristic energies for all available data, both for the magnetic field and temperature dependence of the resistivities. Our results put strong constraints on possible mechanisms responsible for the metallic behavior. In particular, there are strong indications that the system would eventually become insulating at low enough temperature.

two references added, corrected typos, minor changes, final version as published

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• Spin-Droplet State of an Interacting 2D Electron System
• Wigner-Mott scaling of transport near the two-dimensional metal-insulator transition
• Valley polarization assisted spin polarization in two dimensions
• Indication of band flattening at the Fermi level in a strongly correlated electron system
• Quantum phase transition in ultrahigh mobility SiGe/Si/SiGe two-dimensional electron system
• Metal-insulator transition and low-density phases in a strongly-interacting two-dimensional electron system
• Probing spin susceptibility of a correlated two-dimensional electron system by transport and magnetization measurements
• Density-tuned effective metal-insulator transitions in 2D semiconductor layers: Anderson localization or Wigner crystallization
• Spin polarization and exchange-correlation effects in transport properties of two-dimensional electron systems in silicon
• Two-dimensional system of strongly interacting electrons in silicon (100) structures
• Two dimensional electrons in (100) oriented silicon field effect structures in the region of low concentrations and high mobilities
• The effective electron mass in high-mobility SiGe/Si/SiGe quantum wells
• Percolation transition in two dimensional electron gas: A quantum cellular automaton model
• Polarization field in a single-valley strongly-interacting 2D electron system
• Band Flattening and Landau Level Merging in Strongly-Correlated Two-Dimensional Electron Systems