Quantifying many-body effects by high-resolution Fourier transform scanning tunneling spectroscopy

TL;DR

This paper demonstrates high-resolution Fourier transform scanning tunneling spectroscopy (FT-STS) to detect subtle many-body effects in the electronic structure of Ag(111), revealing interactions with lattice vibrations that were previously unresolved.

Contribution

The study introduces a high-resolution FT-STS technique capable of quantitatively detecting many-body interactions in surface states, expanding STM/STS applications.

Findings

Revealed fine structure in Ag(111) surface state dispersion

Detected interaction effects with lattice vibrations

Enhanced understanding of many-body effects at the nano-scale

Abstract

Many-body phenomena are ubiquitous in solids, as electrons interact with one another and the many excitations arising from lattice, magnetic, and electronic degrees of freedom. These interactions can subtly influence the electronic properties of materials ranging from metals, exotic materials such as graphene, and topological insulators, or they can induce new phases of matter, as in conventional and unconventional superconductors, heavy fermion systems, and other systems of correlated electrons. As no single theoretical approach describes all such phenomena, the development of versatile methods for measuring many-body effects is key for understanding these systems. To date, angle-resolved photoemission spectroscopy (ARPES) has been the method of choice for accessing this physics by directly imaging momentum resolved electronic structure. Scanning tunneling microscopy/spectroscopy (STM/S), renown for its real-space atomic resolution capability, can also access the electronic structure in momentum space using Fourier transform scanning tunneling spectroscopy (FT-STS). Here, we report a high-resolution FT-STS measurement of the Ag(111) surface state, revealing fine structure in the otherwise parabolic electronic dispersion. This deviation is induced by interactions with lattice vibrations and has not been previously resolved by any technique. This study advances STM/STS as a method for quantitatively probing many-body interactions. Combined with the spatial sensitivity of STM/STS, this technique opens a new avenue for studying such interactions at the nano-scale.