High-throughput magnetic co-doping and design of exchange interactions in a topological insulator

TL;DR

This study employs high-throughput ab-initio simulations to systematically analyze magnetic impurities in a topological insulator, revealing chemical trends and proposing co-doping as a method to engineer magnetic states for quantum applications.

Contribution

It provides a comprehensive database and analysis of transition metal impurities in Bi2Te3, introducing a high-throughput approach to design magnetic interactions in topological insulators.

Findings

Identification of chemical trends in exchange coupling constants.

Prediction that co-doping can tailor magnetic ground states.

Potential applications in quantum anomalous Hall effects and topological quantum computing.

Abstract

Using high-throughput automation of ab-initio impurity embedding simulations, we created a database of $3d$ and $4d$ transition metal defects embedded into the prototypical topological insulator (TI) Bi$_2$Te$_3$. We simulate both single impurities as well as impurity dimers at different impurity-impurity distances inside the TI. We extract changes to magnetic moments, analyze the polarizability of non-magnetic impurity atoms via nearby magnetic impurity atoms and calculate the exchange coupling constants for a Heisenberg Hamiltonian. We uncover chemical trends in the exchange coupling constants and discuss the impurities' potential with respect to magnetic order in the fields of quantum anomalous Hall insulators and topological quantum computing. In particular, we predict that co-doping of different magnetic dopants is a viable strategy to engineer the magnetic ground state in magnetic TIs.