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

Using high-throughput automation of impurity embedding simulations, we create a database of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mn>3</a:mn><a:mi>d</a:mi></a:mrow></a:math> and <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mn>4</b:mn><b:mi>d</b:mi></b:mrow></b:math> transition metal defects embedded into the prototypical topological insulators (TIs) <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mrow><c:msub><c:mi>Bi</c:mi><c:mn>2</c:mn></c:msub><c:msub><c:mi>Te</c:mi><c:mn>3</c:mn></c:msub></c:mrow></c:math> and <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:mrow><d:msub><d:mi>Bi</d:mi><d:mn>2</d:mn></d:msub><d:msub><d:mi>Se</d:mi><d:mn>3</d:mn></d:msub></d:mrow></d:math>. We simulate both single impurities as well as impurity dimers at different impurity-impurity distances inside the topological insulator matrix. We extract changes to magnetic moments, analyze the polarizability of nonmagnetic 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' abilities with respect to magnetic order in the fields of quantum anomalous Hall insulators and topological quantum computing. In particular, we confirm that co-doping of different magnetic dopants is a viable strategy to engineer the magnetic ground state in magnetic TIs. Published by the American Physical Society 2024