理学院数理讲坛（2018年第08讲）
题 目： Anomalous magnetic transport and extra quantum oscillation in semi-metallic photon-like fermion gas
报告人：虞跃 教授/杰青
单 位：复旦大学物理系
时 间：2018年4月5日（星期四）10:00-11:00
地 点：阳明学院303室
报告摘要：
The dispersionless longitudinal photon in Maxwell theory is thought of as a redundant degree of freedom due to the gauge symmetry. Without the Lorentz symmetry, a photon-like fermionic quasiparticle (feroton) is allowed to emerge in condensed matters and the longitudinal feroton is a dispersionless (at) fermionic zero mode. E_ectively, the many-body charged feroton gas is a semimetal which is a pseudo-spin 1 counterpart of Weyl semimetal. The breakdown of the fermionic gauge symmetry through the feroton _eld coupling to an external magnetic _eld turns the dispersionless feroton to a bunch of gapless elementary excitations each of which carries an n > 1 Landau level index. Since in the long wave length limit these n > 1 gapless excitations are of the opposite chirality to the zero Landau level chiral anomaly mode, rich magnetic transport properties are expected to be observed. When a quadratic perturbation is introduced, an extra low energy quantum oscillation of the density of states is found in addition to the quantum oscillation corresponding to the transverse ferotons. To explore more interesting properties arising from these n > 1 gapless modes, we study an exotic cubic lattice model and _nd that the extra quantum oscillation of the density of states exists even when there are no gaps between low energy Landau bands. We collect known ab initio calculation data from literlature and show the possibility of realization of the semimetallic feroton gas in real materials.