# Chirality Switching in 1T‑TaS2 by Highly Charged Ion Irradiation

## TL;DR

Scientists used highly charged ions to switch the chirality of charge density waves in a material called 1T-TaS2 at low temperatures.

## Contribution

This study demonstrates chirality switching in 1T-TaS2 using Xe8+ ions and provides insights into the underlying electronic and structural changes.

## Key findings

- Xe8+ ions at 22.5 keV switch the chirality of charge density waves in 1T-TaS2 at 50 K.
- Chirality reversal saturates at ≳4000 ions/μm2 with changes in band structure and density of states.
- Ion-induced electronic excitations and defect-stabilized grain boundaries are proposed to drive the chirality switch.

## Abstract

In layered materials, charge density waves can occur
in distinct
chiral phases, which can be switched. We use Xe8+ ions
at a kinetic energy of 22.5 keV to switch the commensurate charge
density wave chirality on the nanoscale in 1T-TaS2 at 50 K. Changes in spectral weight, density of states, and
band structure are monitored in situ by angle-resolved
photoemission spectroscopy. We find that changes in the band structure
are most pronounced at the charge density wave gaps and that chirality
switches gradually with ion fluence, saturating to near-full handedness
reversal at ≳4000 ions/μm2. We discuss a scenario
for ion-induced chiral switching within the framework of intense,
spatially confined electronic excitations, which induce a phase transition
and defect-stabilized grain boundaries.