Effect of high magnetic fields on the electronic structure of density-wave systems

The effect of high magnetic fields on the electronic structure of some quasi-one-dimensional systems with charge- or spin-density waves is examined. Because of the specific anisotropy of the system, small electron and hole pockets created by the density wave can be destroyed by the presence of a magnetic field. This phenomenon is analyzed for various orientations of the field. The energy spectrum and the density of states in the presence of an external field are calculated for a simple quasi-one-dimensional model band structure. The effect of the magnetic field on the density-wave critical temperature is also calculated. Recent experimental results on ${\mathrm{NbSe}}_3$ are analyzed in terms of this theory.