Observation of Surface Fermi Arcs in Weyl Semimetal via Scanning Tunneling Microscopy

Abstract

Weyl semimetals host topologically protected surface states, with arced Fermi surface contours that are predicted to penetrate through the bulk when their momentum matches that of the surface projections of the bulk's Weyl nodes. Here, we describe our experiment in which we used spectroscopic mapping with a scanning tunneling microscope (STM) to visualize quasi-particle interference at the surface of the Weyl semimetal TaAs. Our measurements revealed multitude of scattering wavevectors, which can be reproduced by taking into account the shape and spin texture of the Fermi arc surface states and their momentum-dependent penetration into the bulk. Our result exemplifies an atomic-scale manifestation of surface-bulk connectivity of Weyl semimetal.