Topological surface states in {\gamma}-PtBi$_2$ evidenced by scanning tunneling microscopy

TL;DR

This study provides scanning tunneling microscopy evidence of topological surface states in { extgamma}-PtBi$_2$, revealing their energy positioning near the Fermi level and their topological nature through quasiparticle interference patterns.

Contribution

First direct STM evidence of topological surface states in { extgamma}-PtBi$_2$, confirming their existence and energy location with detailed quasiparticle interference analysis.

Findings

Observation of quasiparticle interference fringes from Fermi arcs

Detection of back-scattering prohibition indicating topological surface states

Localization of surface states within a narrow energy range near the Fermi level

Abstract

For the application of topological materials, the specific location of their topological surface states with respect to the Fermi level are important. {\gamma}-PtBi2 has been demonstrated to be a Weyl semimetal possessing superconducting Fermi arcs by photoemission spectroscopy. However, the evidence of its topological surface states is lacking by scanning tunneling microscopy (STM), which should be rather sensitive to detect the surface states. Here, we show multiple STM evidences for the existence of topological surface states in {\gamma}-PtBi2. We observe not only the step-edge and screw dislocation induced quasiparticle interference fringes, originating from the electron scatterings between the Fermi arcs of {\gamma}-PtBi2, but also the back-scattering prohibition related to the spin-flip process, which is the direct evidence for the topological nature of the surface states. Moreover, we demonstrate that the topological surface states are precisely located over a narrow energy range near the Fermi level, within which sharply enhanced intensity and slow spatial decay of quasiparticle interference are observed.