Spatial Charge Inhomogeneity and Defect States in Topological Dirac Semimetal Thin Films

Abstract

The close approach of the Fermi energy EF of a Dirac semimetal to the Dirac point ED uncovers new physics such as velocity renormalization,1,2,3 and the Dirac plasma 4,5 at |EF -ED| < kBT, where kBT is the thermal energy. In graphene, substrate disorder drives fluctuations in EF. Three-dimensional topological Dirac semimetals (TDS)6,7 obviate the substrate, and should show reduced EF fluctuations due to better metallic screening and higher dielectric constants. Here we map the potential fluctuations in TDS Na3Bi using a scanning tunneling microscope. The rms potential fluctuations are significantly smaller than room temperature (ΔEF,rms = 4-6 meV = 40-70 K) and comparable to the highest quality graphene on h-BN;8 far smaller than graphene on SiO2,9,10 or the Dirac surface state of a topological insulator.11 Surface Na vacancies produce a novel resonance close to the Dirac point with surprisingly large spatial extent and provides a unique way to tune the surface density of states in a TDS thin-film material.

25 pages (7 main manuscript), 9 figues (4 main manuscript)

References in corpus (7)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• STM Spectroscopy of ultra-flat graphene on hexagonal boron nitride
• A self-consistent theory for graphene transport
• Carrier screening, transport, and relaxation in 3D Dirac semimetals
• Charge Puddles in Graphene Near the Dirac Point
• Coulomb disorder in three-dimensional Dirac systems
• Kondo effect and non-Fermi liquid behavior in Dirac and Weyl semimetals

Cited by in corpus (13)

• Electric Field-Tuned Topological Phase Transition in Ultra-Thin Na3Bi - Towards a Topological Transistor
• Dimensional Crossover and Topological Phase Transition in Dirac Semimetal Na3Bi Films
• Progress in epitaxial thin-film Na3Bi as a topological electronic material
• Direct link between disorder, mobility and magnetoresistance in topological semimetals
• Importance of interactions for the band structure of the topological Dirac semimetal Na3Bi
• Defects, band bending and ionization rings in MoS2
• Quantum Transport in Air-stable Na3Bi Thin Films
• Topological Dirac Semimetal Na3Bi Films in the Ultrathin Limit via Alternating Layer Molecular Beam Epitaxy
• Surface orbital order and chemical potential inhomogeneity of the iron-based superconductor FeTe0.55Se0.45 investigated with special STM tips
• Dominant two-dimensional electron-phonon interactions in the bulk Dirac semimetal Na3Bi
• Point defects and their dynamic behaviors in silver monolayer intercalated between graphene and SiC
• Controlling the macroscopic electrical properties of reduced graphene oxide by nanoscale writing of electronic channels
• Topological layered n-type thermoelectrics based on bismuth telluride solid solutions