Destruction of the Field-Induced Density-Wave State in Graphite by Large Magnetic Fields

We have investigated the magnetoresistance of graphite in fields of up to 55 T over the temperature range 1--10 K and obtained clear indications of a reentrant transition from the field-induced density-wave state to the normal state. The reentrant transition is attributed to a Landau subband crossing the Fermi level. We use our experimental data to delineate the phase boundary between the density-wave state and the normal state. We also show that the temperature dependence of the reentrant transition can only be understood using renormalized band structure calculations including self-energy effects. The experimental data also suggest the existence of multiple phases inside the density-wave state.