Zero temperature magnetic phase diagram of Wigner crystal in anisotropic two-dimensional electron systems

Chenggang Zhou, Ravindra N. Bhatt

Research output: Contribution to journalArticle

Abstract

We study the effect of mass anisotropy on the magnetic ordering of the Wigner crystal phase of low density electron systems in two dimensions at T = 0. We apply the instanton approximation to various ring exchange processes, which includes the lowest order Gaussian fluctuations beyond the WKB approximation. The multi-particle exchange frequencies are calculated with effective mass anisotropy, both with and without ensuing lattice distortions. We find that when sufficient mass anisotropy is present, the two-spin exchange process between the nearest neighbors becomes more frequent than the three particle processes. Therefore, its corresponding antiferromagnetic exchange exceeds the ferromagnetic exchange from the three-spin process and becomes dominant. Numerical diagonalization of small clusters with two, three, and four-spin exchange terms shows a transition from a ferromagnetic to an antiferromagnetic ground state with increasing mass anisotropy.

Original languageEnglish (US)
Pages (from-to)1547-1549
Number of pages3
JournalPhysica B: Condensed Matter
Volume403
Issue number5-9
DOIs
StatePublished - Apr 1 2008

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

Keywords

  • Mass anisotropy
  • Ring exchange
  • Two-dimensional electron system
  • Wigner crystal

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