Signature of tilted Dirac cones in Weiss oscillations of $8-Pmmn$ borophene

TL;DR

This paper investigates how tilted Dirac cones in 8-Pmmn borophene influence magnetotransport, revealing enhanced Weiss oscillations and valley polarization effects due to anisotropic tilting.

Contribution

It demonstrates the impact of tilted Dirac cones on Weiss oscillations and valley polarization in borophene's magnetotransport properties, a novel insight into anisotropic 2D materials.

Findings

Tilted Dirac cones modify Weiss oscillation frequency and amplitude.

Weak electric and magnetic modulations induce valley polarization.

Out-of-phase electric and magnetic modulations enhance valley polarization.

Abstract

Polymorph of 8-Pmmn borophene exhibits anisotropic tilted Dirac cones. In this work, we explore the consequences of the tilted Dirac cones in magnetotransport properties of a periodically modulated borophene. We evaluate modulation induced diffusive conductivity by using linear response theory in low temperature regime. The application of weak modulation (electric/magnetic or both) gives rise to the magnetic field dependent non-zero oscillatory drift velocity which causes Weiss oscillation in the longitudinal conductivity at low magnetic field. The Weiss oscillation is studied in presence of an weak spatial electric, magnetic and both modulations individually. The tilting of the Dirac cones gives rise to additional contribution to the Weiss oscillation in longitudinal conductivity. Moreover, it also enhances the frequency of the Weiss oscillation and modifies its amplitude too. Most remarkably, It is found that the presence of out-of phase both i.e., electric and magnetic modulations can cause a sizable valley polarization in diffusive conductivity. The origin of valley polarization lies in the opposite tilting of the two Dirac cones at two valleys.