paper

Quantized Hall conductivity of Bloch electrons: topology and the Dirac fermion

arXiv:cond-mat/9409079 · doi:10.1103/PhysRevB.50.17357

Abstract

We consider the Hall conductivity of two-dimensional non-interacting Bloch electrons when the magnetic flux per unit cell is a rational number where and are mutually coprime. We present a counter-example for the naive expectation that the Hall conductivity carried by a band is given by treating gap minima as Dirac fermions. Instead of the above expectation, we show that the {\em change\/} of the Hall conductivity at a gap-closing phenomenon is given by the Dirac fermion argument. Comparing with the Diophantine equation, our result implies that a band-gap closes at points simultaneously. Furthermore, we show that the dispersion relation is -fold degenerate in the magnetic Brillouin zone.

13pages (REVTeX) + 3 figures (appended as a postscript file), To appear in Phys. Rev. B, ISSP Tech. Rep. Ser.A No.2850

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