Graphite as a Highly Correlated Electron Liquid

Abstract

Although a considerable amount of research work has been done on graphite, its physical properties are still not well understood. In the present paper we review recent reports on the occurrence of magnetic-field-driven metal-insulator and insulator-metal transitions, as well as the quantum Hall effect (QHE) in graphite. The experimental results suggest that the low field (similar to 1 kOe) metal-insulator transition is associated with the transition between Bose metal and excitonic insulator states. On the other hand, the reentrant insulator-metal transition which takes place at higher fields can consistently be understood assuming the occurrence of superconducting correlations caused by the Landau level quantization. We argue that the QHE, observed only for strongly anisotropic quasi-two-dimensional (2D) graphite samples, and superconducting correlations may represent the same phenomenon, implying that Cooper pairs in the quasi-2D samples form a highly correlated boson liquid.