Randomness-induced XY ordering in a graphene quantum hall ferromagnet

Dmitry A. Abanin, Patrick A. Lee, Leonid S. Levitov

Research output: Contribution to journalArticlepeer-review

74 Scopus citations

Abstract

Valley-polarized quantum Hall states in graphene are described by a Heisenberg O(3) ferromagnet model, with the ordering type controlled by the strength and the sign of the valley anisotropy. A mechanism resulting from electron coupling to the strain-induced gauge field, giving a leading contribution to the anisotropy, is described in terms of an effective random magnetic field aligned with the ferromagnet z axis. We argue that such a random field stabilizes the XY ferromagnet state, which is a coherent equal-weight mixture of the K and K′ valley states. The implications such as the Berezinskii-Kosterlitz-Thouless ordering transition and topological defects with half-integer charge are discussed.

Original languageEnglish (US)
Article number156801
JournalPhysical review letters
Volume98
Issue number15
DOIs
StatePublished - Apr 10 2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

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