Density Waves in High Magnetic Fields: A Metal-Insulator Transition

The effect of high magnetic fields on the electronic structure of very anisotropic systems with charge- or spin-density waves is examined. In materials where there is lack of perfect nesting at the Fermi surface the density wave produces small electron and hole pockets. Calculations show that the presence of a high magnetic field in certain directions destroys these pockets, opens a gap in the electronic spectrum at the Fermi level, and leads to a metal-insulator transition. This effect has been recently observed in the low-temperature charge-density-wave phase of NbSe₃.