Theory of metal-insulator transitions in graphite under high magnetic field

Article

关键词: ELECTRONIC PHASE-TRANSITION;    CHARGE-DENSITY-WAVE;    INDUCED LUTTINGER LIQUID;    FERMI LIQUIDS;    EXCITONIC INSULATOR;    TIGHT-BINDING;    STATES;    GAS;    BOSONIZATION;    INSTABILITY;   

DOI  :  10.1103/PhysRevB.98.205121

来源: SCIE

【 摘 要 】

Graphite under high magnetic field exhibits consecutive metal-insulator (MI) transitions as well as reentrant insulator-metal (IM) transitions in the quasiquantum limit at low temperature. In this paper, we identify the low- T insulating phases as excitonic insulators with spin nematic orderings. We first point out that graphite under the relevant field regime is in the charge neutrality region, where electron and hole densities compensate each other. Based on this observation, we introduce interacting electron models with electron pocket(s) and hole pocket(s) and enumerate possible umklapp scattering processes allowed under the charge neutrality. Employing effective boson theories for the electron models and renormalization group analyses for the boson theories, we show that there exist critical interaction strengths above which the umldapp processes become relevant and the system enters excitonic insulator phases with long-range order of spin superconducting phase fields (spin nematic excitonic insulator). We argue that when a pair of electron and hole pockets gets smaller in size, a quantum fluctuation of the spin superconducting phase becomes larger and destabilizes the excitonic insulator phases, resulting in the reentrant IM transitions. We also show that an odd-parity excitonic pairing between the electron and hole pockets reconstructs surface chiral Fermi arc states of electron and hole into a 2-dimensional helical surface state with a gapless Dirac cone. We discuss field and temperature dependencies of in-plane resistance by surface transport via these surface states.

【 授权许可】

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