Room temperature superconductivity dome at a Fano resonance in superlattices of wires

TL;DR

This paper explores how Fano resonances in superlattices of quantum wires can lead to room temperature superconductivity, emphasizing the role of heterostructure electronic states and pressure tuning near topological Lifshitz transitions.

Contribution

It introduces a theoretical perspective on multigap superconductivity at Fano resonances in nanoscale heterostructures, extending beyond conventional BCS and Migdal-Eliashberg models.

Findings

Superconductivity dome peaks at top of pressure-tuned Lifshitz transition.

Fano Feshbach resonance enhances Tc up to room temperature.

Contact exchange interaction is crucial for Tc amplification.

Abstract

Recently room temperature superconductivity with Tc=15 degrees Celsius has been discovered in a pressurized complex ternary hydride, CSHx, which is a carbon doped H3S alloy. The nanoscale structure of H3S is a particular realization of the 1993 patent claim of superlattice of quantum wires for room temperature superconductors where the maximum Tc occurs at the top of a superconducting dome. Here we focus on the electronic structure of materials showing nanoscale heterostructures at atomic limit made of a superlattice of quantum wires like hole doped cuprate perovskites, organics, A15 intermetallics and pressurized hydrides. We provide a perspective of the theory of room temperature multigap superconductivity in heterogeneous materials tuned at a Fano Feshbach resonance (called also shape resonance) in the superconducting gaps focusing on H3S where the maximum Tc occurs where the pressure tunes the chemical pressure near a topological Lifshitz transition. Here the superconductivity dome of Tc versus pressure is driven by both electron-phonon coupling and contact exchange interaction. We show that the Tc amplification up to room temperature is driven by the Fano Feshbach resonance between a superconducting gap in the anti-adiabatic regime and other gaps in the adiabatic regime. In these cases the Tc amplification via contact exchange interaction is the missing term in conventional multiband BCS and anisotropic Migdal-Eliashberg theories including only Cooper pairing