Optically-Controlled Orbitronics on a Triangular Lattice

TL;DR

This paper demonstrates optically-tunable anomalous transport phenomena in a triangular lattice system with orbital multiplets, enabling control over charge and orbital Hall effects through light and potential engineering.

Contribution

It introduces a new mechanism for activating anomalous transport in orbital multiplet systems on a triangular lattice using optical and on-site potentials.

Findings

Optically-tunable potentials induce anomalous charge Hall conductance.

Layer buckling enables anomalous orbital Hall conductance.

Opposite winding number degeneracies are offset in energy, facilitating control.

Abstract

The propagation of electrons in an orbital multiplet dispersing on a lattice can support anomalous transport phenomena deriving from an orbitally-induced Berry curvature. In striking contrast to the related situation in graphene, we find that anomalous transport for an $L=1$ multiplet on the primitive 2D triangular lattice is activated by easily implemented on-site and optically-tunable potentials. We demonstrate this for dynamics in a Bloch band where point degeneracies carrying opposite winding numbers are generically offset in energy, allowing both an anomalous charge Hall conductance with sign selected by off-resonance coupling to circularly-polarized light and a related anomalous orbital Hall conductance activated by layer buckling.