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

¹ RICMASS, Rome International Center for Materials Science Superstripes - via dei Sabelli 119A, 00185 Rome, Italy
² Department of Mathematics and Physics, Roma TRE University - via della Vasca Navale 84, 00146 Rome, Italy
³ DQMP, University of Geneva - 24 Quai Ernest- Ansermet, CH-1211 Geneva 4, Switzerland
⁴ Institute of Crystallography, CNR - via Salaria Km 29.3, I-00016 Monterotondo (Rome), Italy
⁵ National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) - 115409 Moscow, Russia
⁶ Institute for Microelectronics and Microsystems IMM, CNR - via del Fosso del Cavaliere, 100, 00133 Rome, Italy

^(a) antonio.bianconi@ricmass.eu (corresponding author)

Received: 18 February 2021
Accepted: 26 March 2021

Abstract

Recently room temperature superconductivity with degrees Celsius has been discovered in a pressurized complex ternary hydride, CSH_x, which is a carbon- and hydrogen-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 and the maximum T_C occurs at the top of a superconducting dome. Here we focus on the electronic structure of materials showing nanoscale heterostructures at the atomic limit made of a superlattice of quantum wires like hole-doped cuprate perovskites, and organics focusing on A15 intermetallics and pressurized hydrides. We provide a perspective of the theory of room temperature multigap superconductivity in heterogeneous materials tuned at a shape resonance or Fano resonance in the superconducting gaps near a Lifshitz transition focusing on H₃S where the maximum T_C occurs where the multiband metal is tuned by pressure near a Lifshitz transition. Here the superconductivity dome of T_C vs. pressure is driven by both electron-phonon coupling and contact exchange interaction. We show that the T_C amplification up to room temperature is driven by the Fano resonance between a superconducting gap in the anti-adiabatic regime and other gaps in the adiabatic regime. In these cases the T_C amplification via contact exchange interaction is the missing term in conventional multiband BCS and anisotropic Migdal-Eliashberg theories including only Cooper pairing.