Robust and tunable Weyl phases by coherent infrared phonons in ZrTe$_5$

TL;DR

This study demonstrates that infrared phonons can induce and control Weyl phases in ZrTe$_5$, enabling ultrafast topological phase transitions with potential applications in quantum computing and nonlinear electronics.

Contribution

It reveals a method to induce and tune Weyl phases in ZrTe$_5$ via infrared phonon modes, combining first-principles calculations with effective Hamiltonian analysis.

Findings

Infrared phonons can drive ZrTe$_5$ from topological insulator to Weyl semimetal.

Weyl phases are robust, tunable, and near the Fermi level.

Nonlinear effects from Berry curvature dipole enable phonon amplitude control.

Abstract

Ultrafast optical control of the structural and electronic properties of various quantum materials has recently sparked great interest. In particular, photoinduced quantum phase transition between distinct topological phases has been considered as a promising route to realize ultrafast topological quantum computers. Here we use first-principles and effective Hamiltonian methods to show that in ZrTe$_5$, a layered topological material, lattice distortions corresponding to all three types of zone-center infrared optical phonon modes can drive the system from the strong or weak topological insulating phase to a Weyl semimetal by breaking the global inversion symmetry. Thus achieved Weyl phases are robust, highly tunable and one of the cleanest ones due to the proximity of the Weyl points to the Fermi level and a lack of other carriers. We further show that the amount of infrared-mode pumping necessary to induce such Weyl phases can be reduced if used in conjunction with an A$_g$ Raman-mode pumping that first drives the system to the Dirac semimetal state. We also find that Berry curvature dipole moment (BCDM), induced by the dynamical inversion symmetry breaking, gives rise to various nonlinear effects that oscillate with the amplitude of the phonon modes. These nonlinear effects present a novel switch for controlling the Weyltronics enabled quantum system.