# Orbital pseudospin-momentum locking in two-dimensional chiral borophene

## TL;DR

This paper predicts and analyzes a novel orbital pseudospin-momentum locking in chiral borophene, demonstrating control over orbital textures and layer localization via stacking and electric fields, with potential applications in electronic devices.

## Contribution

It introduces the concept of orbital pseudospin-momentum locking in borophene and shows how stacking and electric fields can control orbital textures.

## Key findings

- Orbital textures arise at K/K' points in borophene Dirac bands.
- Layer stacking and electric fields can switch orbital textures on and off.
- Orbital pseudospin is locked with momentum similarly to topological insulator spin textures.

## Abstract

Recently, orbital-textures have been found in Rashba and topological insulator (TI) surface states as a result of the spin-orbit coupling (SOC). Here, we predict a $p_x/p_y$ orbital texture, in linear dispersive Dirac bands, arising at the K/K' points of $\chi$-$h_0$ borophene chiral monolayer. Combining first-principles calculations with effective hamiltonians, we show that the orbital pseudospin has its direction locked with the momentum in a similar way as TIs' spin-textures. Additionally, considering a layer pseudospin degree of freedom, this lattice allows stackings of layers with equivalent or opposite chiralities. In turn, we show a control of the orbital textures and layer localization through the designed stacking and external electric field. For instance, for the opposite chirality stacking, the electric field allows for an on/off switch of the orbital-textured Dirac cone.