Stoner-Type Theory of Magnetism in Silicon MOSFETs

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Abstract

We consider a quasi-two-dimensional gas of electrons in a typical Si-MOSFET, assuming repulsive contact interaction between electrons. Magnetisation and susceptibility are evaluated within the mean-field approach. Finite thickness of the inversion layer results in an interaction-induced electron wave function change, not found in both purely two-dimensional and three-dimensional (bulk) cases. Taking this self-consistent change into account leads to an increased susceptibility and ultimately to a ferromagnetic transition deep in the high-density metallic regime. We further find that in the paramagnetic state, magnetisation increases sublinearly with increasing in-plane magnetic field. In the opposite limit of low carrier densities, the effects of long-range interaction become important and can be included phenomenologically via bandwidth renormalisation. Our treatment then suggests that with decreasing density, the metal–insulator transition is preceded by a ferromagnetic instability. Results are discussed in the context of the available experimental data, and arguments for the validity of our mean-field scheme are presented.

Original languageEnglish
Pages (from-to)67-100
Number of pages34
JournalJournal of Low Temperature Physics
Volume188
Issue number3-4
DOIs
StatePublished - 1 Aug 2017

Keywords

  • 2DEG
  • Ferromagnetism
  • MOSFET
  • Magnetic properties

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Atomic and Molecular Physics, and Optics
  • General Materials Science

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