# Fragility of Fermi arcs in Dirac semimetals

## TL;DR

This study investigates the electronic structure of cubic PtBi₂, revealing the presence of Dirac states and demonstrating that Fermi arcs in Dirac semimetals can be fragile and deform into Fermi contours, confirming theoretical predictions.

## Contribution

The paper provides experimental evidence of the fragility of Fermi arcs in Dirac semimetals, supporting the theory that they can deform into Fermi contours due to lack of topological protection.

## Key findings

- Detection of surface states in PtBi₂ consistent with Dirac semimetal characteristics.
- Observation of Fermi contours replacing double Fermi arcs.
- Confirmation that Fermi arcs are fragile and can deform into Fermi contours.

## Abstract

We use tunable, vacuum ultraviolet laser-based angle-resolved photoemission spectroscopy and density functional theory calculations to study the electronic properties of Dirac semimetal candidate cubic PtBi${}_{2}$. In addition to bulk electronic states we also find surface states in PtBi${}_{2}$ which is expected as PtBi${}_{2}$ was theoretical predicated to be a candidate Dirac semimetal. The surface states are also well reproduced from DFT band calculations. Interestingly, the topological surface states form Fermi contours rather than double Fermi arcs that were observed in Na$_3$Bi. The surface bands forming the Fermi contours merge with bulk bands in proximity of the Dirac points projections, as expected. Our data confirms existence of Dirac states in PtBi${}_{2}$ and reveals the fragility of the Fermi arcs in Dirac semimetals. Because the Fermi arcs are not topologically protected in general, they can be deformed into Fermi contours, as proposed by [Kargarian {\it et al.}, PNAS \textbf{113}, 8648 (2016)]. Our results demonstrate validity of this theory in PtBi${}_{2}$.