Surface Versus Bulk Dirac States Tuning in a Three-Dimensional Topological Dirac Semimetal

TL;DR

This paper demonstrates a method to distinguish and tune surface and bulk Dirac states in the 3D Dirac semimetal Cd3As2 using ARPES and surface deposition, revealing their evolution with doping.

Contribution

It introduces a systematic technique combining ARPES and surface deposition to isolate and control surface and bulk states in a 3D Dirac semimetal.

Findings

Surface and bulk states can be selectively isolated.

Chemical potential tuning affects surface-bulk state degeneracy.

Method enables observation of surface states overlapping with bulk states.

Abstract

Recently, crystalline-symmetry-protected three-dimensional (3D) bulk Dirac semimetal phase has been experimentally identified in a stoichiometric high-mobility compound, Cd3As2. The Dirac state observed in Cd3As2 has been attributed to originate mostly from the bulk state while calculations show that the bulk and surface states overlap over the entire Dirac dispersion energy range. In this study, we unambiguously reveal doping induced evolution of the ground state of surface and bulk electron dynamics in a 3D Dirac semimetal. We develop a systematic technique to isolate the surface and bulk states in Cd3As2, by simultaneously utilizing angle-resolved photoemission spectroscopy (ARPES) and in-situ surface deposition. Our experimental results provide a method for tuning the chemical potential as well as to observe surface states degenerate with bulk states, which will be useful for future applications of 3D Dirac semimetal.