We have a new preprint on the arXiv: https://arxiv.org/abs/2607.20030

How to measure loop currents in scanning tunneling microscopy”
Victoire Morisseau, Luke C. Rhodes, Peter Wahl, Carolina A. Marques.

Loop currents are the proposal that electrons can flow in closed loops within a material, producing tiny magnetic fields. If they exist, loop currents could explain a variety of correlated phenomena—most notably the pseudogap in the cuprates. But detecting them experimentally has been remarkably difficult.

Following on from the success of our open-source CalcQPI software, which has enabled detailed quantitative comparisons between theoretical models and experimental scanning tunneling microscopy measurements, we turned our attention to loop currents. We asked the question: if loop currents are present in a material, what would we see in an STM measurement?

Using CalcQPI, we can take electronic structure models with loop currents in them and compare their results to models without loop currents. This allowed us to extract the exact quantitative signatures one would expect to see if loop currents are present. We even propose spin-polarised STM as one of the clearest ways to measure loop currents experimentally.

The success of this project is down to Dr Carolina Marques, who led this project and pushed it through to completion as well as Victoire Morisseau who studied this in detail during her Bachelor’s dissertation. It turned into a fantastic piece of work!

Check out the full publication on arXiv: https://arxiv.org/abs/2607.20030

Image credit to Dr Carolina Marques