Speaker
Description
In quantum materials research, exploiting electronic interactions is key to tuning systems toward interesting phases. However, describing correlations in interacting lattice systems remains notoriously difficult, posing challenges for both precise theoretical descriptions and the interpretation of experimental data. In this work, we investigate the effect of higher-order Van Hove singularities (HOVHS) on a single magnetic impurity embedded in a superconducting host. This system serves as a promising platform, as it is accessible to both advanced theoretical methods and high-precision scanning tunneling microscopy (STM) experiments, allowing for reliable and verifiable predictions.
The physics of magnetic impurities in superconductors is governed by the competition between Kondo screening and superconducting pairing. This interplay typically drives a quantum phase transition between a screened singlet ground state and an unscreened phase, the latter being characterized by the formation of Yu-Shiba-Rusinov (YSR) in-gap states [1,2]. Using numerical renormalization group calculations, we demonstrate that the quantum critical point shifts toward larger values of the superconducting pairing strength with an increasing singularity exponent. Our findings indicate that the tuning of Van Hove singularities is a potential mechanism for controlling quantum phase transitions in doped superconductors.
[1] K. Satori, H. Shiba, O. Sakai, Y. Shimizu, J. Phys. Soc. Jpn. 61, 3239 (1992).
[2] C. P. Moca, I. Weymann, M. A. Werner, G. Zaránd, Phys. Rev. Lett. 127, 186804 (2021).
This work was supported by the National Science Centre, Poland, under project No. 2023/51/D/ST3/00532.