Ab initio study of the nonlinear optical properties and d.c. photocurrent of the Weyl semimetal TaIrTe$_4$

TL;DR

This paper uses first-principles nonlinear response theory to analyze the d.c. photocurrent and optical effects in the Weyl semimetal TaIrTe4, identifying the jerk current as a key contributor to its large photoconductivity.

Contribution

It provides a comprehensive theoretical analysis of nonlinear optical effects and photocurrents in TaIrTe4, highlighting the role of jerk current in its large photoconductivity.

Findings

Jerk current likely causes large photoconductivity in TaIrTe4.

Second-order effects include shift and injection currents.

Third-order effects involve current-induced shift, injection, and jerk currents.

Abstract

We present a first principles theoretical study employing nonlinear response theory to investigate the d.c. photocurrent generated by linearly polarized light in the type-II Weyl semimetal TaIrTe4. We report the low energy spectrum of several nonlinear optical effects. At second-order, we consider the shift and injection currents. Assuming the presence of a built-in static electric field, at third-order we study the current-induced shift and injection currents, as well as the jerk current. We discuss our results in the context of a recent experiment measuring an exceptionally large photoconductivity in this material [J. Ma et at., Nat. Mater. 18, 476 (2019)]. According to our results, the jerk current is the most likely origin of the large response. Finally, we propose means to discern the importance of the various mechanisms involved in a time-resolved experiment.