SPONTANEOUS LATTICE DEFORMATION IN THE HOFSTADTER SYSTEM

In this paper, a lattice deformation model for the Hofstadter system i s proposed to study the effects of lattice deformation on an electroni c system coupled with a magnetic field. Uniform lattice deformation ne cessarily occurs in this model so that it causes the flux in a plaquet te lock in to a rational value in a unit of a flux quantum. Then the H all conductance, which is always integer times e(2)/(h) over bar, is a lso locked. In addition to the uniform lattice deformation, the Peierl s instability induces nonuniform lattice deformation at some electron density. The conditions for the occurrence of nonuniform lattice defor mation are also given in terms of elastic constants, electron density, and the applied magnetic field.