• Mazziotti, Maria Vittoria

Abstract

<jats:title>Abstract</jats:title><jats:p>Recently room temperature superconductivity with <jats:inline-formula id="epl20559ieqn1"><jats:tex-math><?CDATA $T_C=15$ ?></jats:tex-math><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="epl20559ieqn1.gif" xlink:type="simple" /></jats:inline-formula> degrees Celsius has been discovered in a pressurized complex ternary hydride, CSH<jats:sub><jats:italic>x</jats:italic></jats:sub>, which is a carbon- and hydrogen-doped H<jats:sub>3</jats:sub>S alloy. The nanoscale structure of H<jats:sub>3</jats:sub>S is a particular realization of the 1993 patent claim of superlattice of quantum wires for room temperature superconductors and the maximum <jats:italic>T</jats:italic><jats:sub><jats:italic>C</jats:italic></jats:sub> 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 <jats:italic>A</jats:italic>15 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 H<jats:sub>3</jats:sub>S where the maximum <jats:italic>T</jats:italic><jats:sub><jats:italic>C</jats:italic></jats:sub> occurs where the multiband metal is tuned by pressure near a Lifshitz transition. Here the superconductivity <jats:italic>dome</jats:italic> of <jats:italic>T</jats:italic><jats:sub><jats:italic>C</jats:italic></jats:sub> <jats:italic>vs.</jats:italic> pressure is driven by both electron-phonon coupling and contact exchange interaction. We show that the <jats:italic>T</jats:italic><jats:sub><jats:italic>C</jats:italic></jats:sub> 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 <jats:italic>T</jats:italic><jats:sub><jats:italic>C</jats:italic></jats:sub> amplification via contact exchange interaction is the missing term in conventional multiband BCS and anisotropic Migdal-Eliashberg theories including only Cooper pairing.</jats:p>

Topics

• perovskite
• impedance spectroscopy
• Carbon
• theory
• anisotropic
• Hydrogen
• intermetallic
• wire
• superconductivity
• superconductivity
• quantum wire