Surface spectroscopy and surface-bulk hybridization of Weyl semimetals

TL;DR

This paper develops an exact analytical framework to understand surface-bulk hybridization in Weyl semimetals, revealing universal spectral features and critical responses relevant for spectroscopic experiments.

Contribution

It introduces a unified formalism for surface-bulk hybridization in Weyl semimetals, enabling analytical predictions of spectral signatures in spectroscopic measurements.

Findings

Universal spectral information from surface states

Inhomogeneous responses near Weyl points

Guidance for spectroscopic identification of hybridization

Abstract

Weyl semimetal showing open-arc surface states is a prominent example of topological quantum matter in three dimensions. With the bulk-boundary correspondence present, nontrivial surface-bulk hybridization is inevitable but less understood. Spectroscopies have been often limited to verifying the existence of surface Fermi arcs, whereas its spectral shape related to the hybridization profile in energy-momentum space is not well studied. We present an exactly solvable formalism at the surface for a wide range of prototypical Weyl semimetals. The resonant surface state and the bulk influence coexist as a surface-bulk hybrid and are treated in a unified manner. Directly accessible to angle-resolved photoemission spectroscopy, we analytically reveal universal information about the system obtained from the spectroscopy of resonant topological states. We systematically find inhomogeneous and anisotropic singular responses around the surface-bulk merging borderline crossing Weyl points, highlighting its critical role in the Weyl topology. The response in scanning tunneling spectroscopy is also discussed. The results will provide much-needed insight into the surface-bulk-coupled physical properties and guide in-depth spectroscopic investigation of the nontrivial hybrid in many topological semimetal materials.