Optical and magnetic signatures of the topological edge states in a dimerised donor chain

TL;DR

This study demonstrates how tuning inter-donor distances in a one-dimensional donor chain induces a topological phase transition, affecting optical spectra and revealing edge states with potential applications in designing topological materials.

Contribution

It introduces a comprehensive theoretical analysis including beyond-Hubbard models, predicting optical signatures of topological edge states in donor chains.

Findings

Topological phase transition induced by inter-donor distance tuning.

Optical spectra signatures correlate with the topological phase transition.

Edge states support a robust 1s→2p atomic transition.

Abstract

We have studied the excited states of a one-dimensional donor dimer array by using time-dependent Hartree-Fock and density-functional theories. We find that tuning the inter-donor distances can induce a topological phase transition from a topologically trivial anti-ferromagnetic ground state to a topological phase supporting spin-polarised edge states. Significant changes in the optical spectra accompany this transition, providing signatures for the phase transition and the existence of the edge state; the edge states lead to a robust $1s\rightarrow 2p$ atomic transition. By contrast, the bulk of the chain becomes spinless, inducing a reduction in the HOMO-LUMO gap and a decrease of the excitation energies in the optical spectra. The inclusion of physics beyond the Su-Schrieffer-Heeger-Hubbard model (long-range electron correlations and basis states beyond the 1s manifold) has a critical effect on the results and leads to the novel prediction of a change in optical response related to a topological phase transition. Our results provide a theoretical foundation for using artificial donor linear arrays in semiconductors to form topological edge states by design.