Origin of the impurity-induced thermoelectric enhancement

Determine whether hybridization between impurity-induced bound states is responsible for the altered and enhanced Seebeck response of superconductors containing multiple nonmagnetic impurities, by resolving how the electronic structure changes when several impurities are present.

Background

The paper studies the local Seebeck coefficient of s-wave and d-wave superconductors containing two nonmagnetic impurities at variable separation. Although the thermoelectric response changes with impurity proximity and can increase by approximately 30% for the parameters considered, the authors do not establish that this enhancement results from hybridization of impurity-bound states.

The uncertainty is especially important for the s-wave case, where the impurity-induced bound state is strongly localized and the calculated local density of states shows no apparent hybridization-related enhancement of particle-hole asymmetry. The authors suggest that the increased response may instead arise from the combined effects of nearby impurities and the spatial sensitivity of the modeled STM probe. Further analysis of the multi-impurity electronic structure is therefore required to identify the microscopic mechanism.

References

While the calculations indicate that the thermoelectric response is altered, even enhanced for small enough separation distances, we do not consider this conclusive proof that hybridization effects are the origin of this. To investigate this further, one would have to look closer at how the electronic structure is modified by the presence of several impurities.

— Quantum interference between vortex- and impurity-bound states boosts thermoelectricity  (2609.10687 - Haatuft et al., 9 Sep 2026) in Section “Results: Impurity-bound states”