Realistic modeling of the electronic structure and the effect of correlations for Sn/Si(111) and Sn/Ge(111) surfaces

TL;DR

This study combines density-functional theory with many-body methods to model the electronic structure and correlations in Sn/Si(111) and Sn/Ge(111) surfaces, revealing magnetic ordering and the effects of electron interactions.

Contribution

It introduces a comprehensive approach using DFT and many-body techniques to explicitly model correlations and magnetic states in Sn surface systems, advancing understanding of their electronic properties.

Findings

Stable 120° antiferromagnetic order in ground state

Finite Hubbard U influences surface state properties

Explicit low-energy models capture correlation effects

Abstract

The correlated electronic structure of the submonolayer surface systems Sn/Si(111) and Sn/Ge(111) is investigated by density-functional theory (DFT) and its combination with explicit many-body methods. Namely, the dynamical mean-field theory and the slave-boson mean-field theory are utilized for the study of the intriguing interplay between structure, bonding and electronic correlation. In this respect, explicit low-energy one- and four($sp^2$-like)-band models are derived using maximally-localized Wannier(-like) functions. In view of the possible low-dimensional magnetism in the Sn submonolayers we compare different types of magnetic orders and indeed find a 120$^\circ$ antiferromagnetic ordering to be stable in the ground state. With single-site methods and cellular-cluster extensions the influence of a finite Hubbard $U$ on the surface states in a planar and a reconstructed structural geometry is furthermore elaborated.