Probing quantum geometry through optical conductivity and magnetic circular dichroism.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39693437.
- Also identified by DOI 10.1126/sciadv.ado1761 and PMC identifier 13108739.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Probing ground-state quantum geometry and topology through optical responses is not only of fundamental interest, but it can also offer several practical advantages. Here, using first-principles calculations on thin films of the antiferromagnetic topological insulator MnBi<sub>2</sub>Te<sub>4</sub>, we demonstrate how the generalized optical weight arising from the absorptive part of the optical conductivity can be used to probe the ground-state quantum geometry and topology. We show that three-septuple-layer MnBi<sub>2</sub>Te<sub>4</sub> film exhibit an enhanced, almost-perfect magnetic circular dichroism for a narrow photon energy window in the infrared region. We calculate the quantum weight in this MnBi<sub>2</sub>Te<sub>4</sub> film and show that it far exceeds the lower bound provided by the Chern number. Our results suggest that the well-known optical methods are powerful tools for probing the ground-state quantum geometry and topology.