Valley-polarized magnetoconductivity and particle-hole symmetry breaking in a periodically modulated α-T3 lattice
AbstractWe explore the transport properties of a periodically modulated α-T3 lattice in the presence of a perpendicular magnetic field. The effect of the Berry phase on electrical conductivity oscillation, so-called Weiss oscillation, caused by the modulation-induced nonzero drift velocity of charge carriers is investigated. Employing linear response theory within the low-temperature regime, we analyze Weiss oscillation as a function of the external magnetic field for both electrically and magnetically modulated α-T3 lattices numerically as well as analytically. The Berry phase makes this hexagonal lattice structure behave differently than other two-dimensional fermionic systems. It causes a significant valley polarization in magnetoconductivity. Most interestingly, the combined effect of both modulations breaks the particle-hole symmetry and causes a smooth transition from even (odd) to odd (even) filling fraction corresponding to the density of states peaks by means of the Berry phase.