All-optical nonequilibrium pathway to stabilizing magnetic Weyl semimetals in pyrochlore iridates

TL;DR

This paper proposes a novel nonequilibrium method using ultrafast laser pulses to induce and stabilize magnetic Weyl semimetal phases in pyrochlore iridates, bypassing the need for Floquet states.

Contribution

It introduces a realistic, nonequilibrium pathway to create Weyl semimetals through laser-controlled modification of electron interactions and magnetic order.

Findings

Transient Weyl cones emerge under laser-driven magnetic order changes.

Time-dependent Hubbard U calculations show effective interaction modification.

Potential for ultrafast switching of topological properties in materials.

Abstract

Nonequilibrium many-body dynamics is becoming one of the central topics of modern condensed matter physics. Floquet topological states were suggested to emerge in photodressed band structures in the presence of periodic laser driving. Here we propose a viable nonequilibrium route without requiring coherent Floquet states to reach the elusive magnetic Weyl semimetallic phase in pyrochlore iridates by ultrafast modification of the effective electron-electron interaction with short laser pulses. Combining \textit{ab initio} calculations for a time-dependent self-consistent reduced Hubbard $U$ controlled by laser intensity and nonequilibrium magnetism simulations for quantum quenches, we find dynamically modified magnetic order giving rise to transiently emerging Weyl cones that are probed by time- and angle-resolved photoemission spectroscopy. Our work offers a unique and realistic pathway for nonequilibrium materials engineering beyond Floquet physics to create and sustain Weyl semimetals. This may lead to ultrafast, tens-of-femtoseconds switching protocols for light-engineered Berry curvature in combination with ultrafast magnetism.