Fermi-Level Pinning, Charge Transfer, and Relaxation of Spin-Momentum Locking at Metal Contacts to Topological Insulators

Abstract

Topological insulators are of interest for many applications in electronics and optoelectronics, but harnessing their unique properties requires detailed understanding and control of charge injection at electrical contacts. Here we present large-scale ab initio calculations of the electronic properties of Au, Ni, Pt, Pd, and graphene contacts to Bi2Se3. We show that regardless of the metal, the Fermi level is located in the conduction band, leading to n-type Ohmic contact to the first quintuplet. Furthermore, we find strong charge transfer and band-bending in the first few quintuplets, with no Schottky barrier for charge injection even when the topoplogical insulator is undoped. Our calculations indicate that Au and graphene leave the spin-momentum locking mostly unaltered, but on the other hand, Ni, Pd, and Pt strongly hybridize with Bi2Se3 and relax spin-momentum locking. Our results indicate that judicious choice of the contact metal is essential to reveal the unique surface features of topological insulators.

arXiv commentManuscript + Supplemental Material

References in corpus (15)

• Topological Insulators
• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• Spintronics and Pseudospintronics in Graphene and Topological Insulators
• Control over topological insulator photocurrents with light polarization
• A topological insulator surface under strong Coulomb, magnetic and disorder perturbations
• Spin Polarization and Transport of Surface States in the Topological Insulators Bi2Se3 and Bi2Te3 from First Principles
• Emergent quantum confinement at topological insulator surfaces
• Photoemission Spectroscopy of Magnetic and Non-magnetic Impurities on the Surface of the Bi${}_2$Se${}_3$ Topological Insulator
• Two-dimensional surface charge transport in topological insulators
• First Principles Investigations of the Atomic, Electronic, and Thermoelectric Properties of Equilibrium and Strained Bi2Se3 & Bi2Te3, with van der Waals Interactions
• Insulating behavior in ultra-thin bismuth selenide field effect transistors
• Proximity effect in graphene-topological insulator heterostructures
• Photoelectron spin-polarization-control in the topological insulator Bi2Se3
• Bulk metals with helical surface states

Cited by in corpus (14)

• Transport in two-dimensional topological materials: recent developments in experiment and theory
• Proximity band structure and spin textures on both sides of topological-insulator/ferromagnetic-metal interface and their transport probes
• Giant Edelstein effect in Topological-Insulator--Graphene heterostructures
• Evaluating the exfoliation of two-dimensional materials with a Green's function surface model
• Highly efficient spin-to-charge current conversion at room temperature in strained HgTe surface states
• Hybridization-induced interface states in a topological insulator-magnetic metal heterostructure
• Spin-orbit-proximitized ferromagnetic metal by monolayer transition metal dichalcogenide: Atlas of spectral functions, spin textures and spin-orbit torques in Co/MoSe${}_2$, Co/WSe${}_2$ and Co/TaSe${}_2$ heterostructures
• A Molecular Approach for Engineering Interfacial Interactions in Magnetic-Topological Insulator Heterostructures
• High density carriers at a strongly coupled graphene-topological insulator interface
• Growth, Morphology and Stability of Au in Contact with the Bi2Se3(0001) Surface
• Atomistic study of an ideal metal/thermoelectric contact: the full-Heusler/half-Heusler interface
• Electrical detection of spin-polarized current in topological insulator Bi1.5Sb0.5Te1.7Se1.3
• Double Fe-impurity charge state in the topological insulator Bi${}_2$Se${}_3$
• Induced Spin-texture at 3$d$ Transition Metal/Topological Insulator Interfaces