Spin- and valley-dependent analysis of the two-dimensional low-density electron system in Si MOSFETs

2004/02/09 by M. W. C. Dharma‐wardana, M. W. C. Dharma-wardana, F. Perrot +1 · 2 citations
Engineering · Materials Science · Physics and Astronomy · #Quantum and electron transport phenomena #Semiconductor materials and devices #ZnO doping and properties #cond-mat.mes-hall #cond-mat.mtrl-sci #cond-mat.str-el

paper · pdf · doi:10.1103/physrevb.70.035308

published as Phys. Rev. B, vol 70, 35308 (2004) with extra figure, revisions. · 10 pages 4 figures

arxiv created 2004/02/09 · openalex publication_date 2004/07/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

The two-dimensional electron system (2DES) in Si metal-oxide field-effect transistors consists of two distinct electron fluids interacting with each other. We calculate the total energy as a function of the density n and the spin polarization \ensuremathζ in the strongly correlated low-density regime, using a classical mapping to a hypernetted-chain (CHNC) equation inclusive of bridge terms. The ten distribution functions arising from spin and valley indices are calculated to obtain the total free energy, the chemical potential, the compressibility, and the spin susceptibility. The T=0 results are compared with the two-valley quantum Monte Carlo (QMC) data of Conti and Senatore [Europhys. Lett. 36, 695 (1996)] (at T=0, \ensuremathζ=0) and found to be in excellent agreement. Unlike in the one-valley 2DES, it is shown that the unpolarized phase is always the stable phase in the two-valley system, right up to Wigner crystallization at r_s\ensuremath∼40. Hence g^* is insensitive to the spin polarization and to the density. The compressibility and the spin-susceptibility enhancement calculated from the free energy validate a simple approach to the two-valley response based on coupled-mode formation. The local-density approximation of density-functional theory is shown to fail, especially near r_s=1, even though the 2DES is uniform. The spin-susceptibility enhancement calculated from the coupled-valley response and directly from the two-valley energies is discussed. The three methods, QMC, CHNC, and coupled-mode theory, agree closely. Our results contain no ad hoc fit parameters and lead to general agreement with available experimental results.

Cited by

• The uniform electron gas at warm dense matter conditions
• Ground state of clean and defective graphene: Coulomb interactions, pair-distribution functions, and spin-polarized phases of massless Dirac fermions

Related

• Spin properties of a two dimensional electron system: valley degeneracy and finite thickness effects
• Thermodynamic magnetization of a strongly interacting two-dimensional system
• Novel Energy Scale in the Interacting 2D Electron System Evidenced from Transport and Thermodynamic Measurements
• Metal-insulator transition in a strongly-correlated two-dimensional electron system
• Absence of Ferromagnetic Instability at the Metal-Insulator Transition in Si-inversion Layers