Enhanced Andreev reflection in flat-band systems: Wave packet dynamics, dc transport, and the Josephson effect
Phys. Rev. B 113, 134517 – Published 17 April, 2026
DOI: https://doi.org/10.1103/qr7p-c56y
Abstract
We investigate Andreev reflection (AR) in a proximity-induced normal-superconductor (NS) junction within the extended lattice, emphasizing the impact of flat bands on AR. Our findings reveal that flat bands significantly enhance AR. Through wave-packet dynamics, we track the real-time evolution of quasiparticle wave packets across the junction, providing deeper insight into electron-hole conversion. Notably, the combination of band flatness and anisotropic dispersion in the plane induces an electronic analog of Goos-Hänchen (GH) shifts at the NS interface, exhibiting directional asymmetry along the junction. This asymmetry leads to a Hall-like response in a Josephson junction in the superconductor–normal-metal–superconductor geometry, where transport across the junction region is dominated by the quasiflat bands.