# Optical signature of Weyl electronic structures in tantalum pnictides Ta$Pn$ ($Pn=$ P, As)

## TL;DR

This study measures optical conductivity spectra of Weyl semimetals TaP and TaAs, revealing features linked to Weyl points and their energy positions relative to the Fermi level through experimental data and band calculations.

## Contribution

It provides detailed optical spectra analysis of TaP and TaAs, connecting spectral features to Weyl point structures and their energy locations, advancing understanding of their electronic structures.

## Key findings

- Weyl points in TaAs are near the Fermi level.
- Distinct optical features correspond to interband transitions at Weyl points.
- Temperature dependence reveals differences in Weyl point energies between TaP and TaAs.

## Abstract

To investigate the electronic structure of Weyl semimetals Ta$Pn$ ($Pn=$P, As), optical conductivity [$\sigma(\omega)$] spectra are measured over a wide range of photon energies and temperatures, and these measured values are compared with band calculations. Two significant structures can be observed: a bending structure at $\hbar\omega\sim$85 meV in TaAs, and peaks at $\hbar\omega\sim$ 50 meV (TaP) and $\sim$30 meV (TaAs). The bending structure can be explained by the interband transition between saddle points connecting a set of $W_2$ Weyl points. The temperature dependence of the peak intensity can be fitted by assuming the interband transition between saddle points connecting a set of $W_1$ Weyl points. Owing to the different temperature dependence of the Drude weight in both materials, it is found that the Weyl points of TaAs are located near the Fermi level, whereas those of TaP are further away.