Correlation-driven Metal-Insulator Transition in Graphite Under High Magnetic Field

Graphite under high magnetic field exhibits a metal-insulator transition as well as insulator-metal re-entrant transition in the quasi-quantum limit at low temperature. The Hall conductivity experiment suggests that the electronic system is nearly in the charge-neutrality point. To explain the re-entrant transition, we employ a model with two-electron pockets and two-hole pockets, to construct a bosonized Hamiltonian that comprises of displacement fields along the field direction. We enumerate all possible umklapp progresses in which both the electron and hole pockets are involved and which are allowed in the model under the charge neutrality condition. Using the variational method and renormalization group argument, we show that there exists a critical interaction strength above which the umklapp terms become relevant, and the system enters a Mott insulator phase with spin nematic order. By showing how the critical interaction strength depends on Luttinger parameters of each pockets and temperature, we give a simple phenomenology of the insulator-metal re-entrant transition in graphite under high field.