Ultrafast manipulation of mirror domain walls in a charge density wave

TL;DR

This paper demonstrates ultrafast, reversible manipulation of mirror domain walls in a charge density wave material using femtosecond laser pulses, enabling precise control over material properties at room temperature.

Contribution

It introduces a method to locally write and erase domain walls in a charge density wave using ultrafast light pulses, a novel approach for dynamic material engineering.

Findings

Single femtosecond pulses can inject or remove domain walls.

Domain wall manipulation affects CDW oscillation frequencies.

The process is tunable by pulse energy and temperature.

Abstract

Domain walls (DWs) are singularities in an ordered medium that often host exotic phenomena such as charge ordering, insulator-metal transition, or superconductivity. The ability to locally write and erase DWs is highly desirable, as it allows one to design material functionality by patterning DWs in specific configurations. We demonstrate such capability at room temperature in a charge density wave (CDW), a macroscopic condensate of electrons and phonons, in ultrathin 1T-TaS$_2$. A single femtosecond light pulse is shown to locally inject or remove mirror DWs in the CDW condensate, with probabilities tunable by pulse energy and temperature. Using time-resolved electron diffraction, we are able to simultaneously track anti-synchronized CDW amplitude oscillations from both the lattice and the condensate, where photo-injected DWs lead to a red-shifted frequency. Our demonstration of reversible DW manipulation may pave new ways for engineering correlated material systems with light.