# Valley-polarized magnetoconductivity and particle-hole symmetry breaking in a periodically modulated $\alpha$-$\mathcal{T}_3$ lattice

## TL;DR

This paper investigates how Berry phase influences Weiss oscillations and valley polarization in a periodically modulated $ ext{α-} ext{T}_3$ lattice under magnetic fields, revealing particle-hole symmetry breaking and novel transport phenomena.

## Contribution

It provides a detailed analysis of Berry phase effects on magnetoconductivity and valley polarization in a modulated $ ext{α-} ext{T}_3$ lattice, highlighting particle-hole symmetry breaking.

## Key findings

- Berry phase induces valley polarization in magnetoconductivity.
- Combined modulations break particle-hole symmetry.
- Transition from even to odd filling fractions observed.

## Abstract

We explore the transport properties of a periodically modulated $\alpha$-$\mathcal{T}_3$ 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 non-zero 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 $\alpha$-$\mathcal{T}_3$ lattice 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.