# Low-Energy Optical Conductivity of TaP: Comparison of Theory and Experiment

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## Abstract

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## 1. Introduction

## 2. Results and Discussion

**k**point, the bands are numbered with increasing energy staring from the lowest calculated band). Note that the bands in each of the two pairs, (19, 20) and (21, 22), are split by SOC because of the lack of inversion symmetry. Our results reproduce well the published band structures of TaP calculated using the full-potential codes [11,13].

^{−1}at $\Delta {E}_{F}=50$ meV.

**k**-vectors faraway from the Weyl nodes; closer to the nodes, SOC is strong and spin polarization is much less perfect. Thus, transitions between any pair of bands are allowed there.

## 3. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 1.**(

**a**) Crystallographic structure of TaP and (

**b**) a schematic diagram of its Weyl bands. Possible transitions between the saddle points of the merging Weyl bands and between the SOC-split bands are indicated as arrows.

**Figure 2.**(

**a**) Experimental in-plane reflectivity and (

**b**) the corresponding real part of the optical conductivity of TaP at selected temperatures [35]. The arrows mark the feature discussed in this paper. The increased ${\sigma}_{1xx}$ at low energies is due to intraband (Drude-like) absorption.

**Figure 3.**(

**a**) Brillouin zone of TaP. (

**b**) Fermi surface cross sections calculated for $\Delta {E}_{F}=50$ meV. Black circles show approximate positions of projections of Weyl points onto ${k}_{y}=0$ plane. (

**c**) Band structure of TaP. Four bands closest to ${E}_{F}$ (marked 19 to 22) are shown in different colors. Black and red horizontal dashed lines show the as-calculated position of ${E}_{F}$ and the Fermi level shifted upwards by $\Delta {E}_{F}=50$ meV, respectively.

**Figure 4.**Low-energy optical conductivity of TaP calculated from its band structure. Lines of different colors correspond to different positions of the Fermi level, as indicated. The conductivity calculated for smaller positive $\Delta {E}_{F}$ is plotted in the inset. The contributions of $21\to 22$ transitions are shown by dashed lines.

**Figure 5.**Temperature dependence of the optical conductivity calculated (

**a**) by multiplying the interband transition probabilities with the Fermi-Dirac function and (

**b**) using the Mott formula.

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Yaresko, A.; Pronin, A.V.
Low-Energy Optical Conductivity of TaP: Comparison of Theory and Experiment. *Crystals* **2021**, *11*, 567.
https://doi.org/10.3390/cryst11050567

**AMA Style**

Yaresko A, Pronin AV.
Low-Energy Optical Conductivity of TaP: Comparison of Theory and Experiment. *Crystals*. 2021; 11(5):567.
https://doi.org/10.3390/cryst11050567

**Chicago/Turabian Style**

Yaresko, Alexander, and Artem V. Pronin.
2021. "Low-Energy Optical Conductivity of TaP: Comparison of Theory and Experiment" *Crystals* 11, no. 5: 567.
https://doi.org/10.3390/cryst11050567