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Tuning phase transition between quantum spin Hall and ordinary insulating phases

2007/05/31 by Shuichi Murakami, Satoshi Iso, Y. Avishai +3 · 9 citations
Materials Science · Physics and Astronomy · #Graphene research and applications #Quantum and electron transport phenomena #Topological Materials and Phenomena #cond-mat.mes-hall #hep-th

paper · pdf · doi:10.1103/physrevb.76.205304

published as Phys.Rev.B76:205304,2007 · 6 pages, 2 figures, to appear in Phys. Rev. B

arxiv created 2007/10/11 · openalex publication_date 2007/11/02 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01

Abstract

An effective theory is constructed for analyzing a generic phase transition between the quantum spin Hall and the insulator phases. Occurrence of degeneracies due to closing of the gap at the transition are carefully elucidated. For systems without inversion symmetry the gap closing occurs at \ifmmode±\else\textpm\fi\stackrelPk0(\ensuremath≠\stackrelPG∕2) while for systems with inversion symmetry, the gap can close only at wave numbers \stackrelPk=\stackrelPG∕2, where \stackrelPG is a reciprocal lattice vector. In both cases, following a unitary transformation which mixes spins, the system is represented by two decoupled effective theories of massive two-component fermions having masses of opposite signs. Existence of gapless helical modes at a domain wall between the two phases directly follows from this formalism. This theory provides an elementary and comprehensive phenomenology of the quantum spin Hall system.

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