Resonant multi-gap superconductivity at room temperature near a Lifshitz topological transition in sulfur hydrides

Abstract

The maximum critical temperature for superconductivity in pressurized hydrides appears at the top of superconducting domes in Tc vs pressure curves at a particular pressure, which is not predicted by standard superconductivity theories. The high-order anisotropic Van Hove singularity near the Fermi level observed in band-structure calculations of pressurized sulfur hydride, typical of a supermetal, has been associated with the array of metallic hydrogen wire modules forming a nanoscale heterostructure at an atomic limit called the superstripe phase. Here, we propose that pressurized sulfur hydrides behave as a heterostructure made of a nanoscale superlattice of interacting quantum wires with a multicomponent electronic structure. We present first-principles quantum calculation of a universal superconducting dome where Tc amplification in multi-gap superconductivity is driven by the Fano–Feshbach resonance due to a configuration interaction between open and closed pairing channels, i.e., between multiple gaps in the BCS regime, resonating with a single gap in the BCS–Bose–Einstein condensation crossover regime. In the proposed three dimensional phase diagram, the critical temperature shows a superconducting dome where Tc is a function of two variables: (i) the Lifshitz parameter (η) measuring the separation of the chemical potential from the Lifshitz transition normalized by the inter-wire coupling and (ii) the effective electron–phonon coupling (g) in the appearing new Fermi surface including phonon softening. The results will be of help for material design of room-temperature superconductors at ambient pressure.

BCS-BCS crossover between atomic and molecular superfluids in a Bose-Fermi mixture

“…Apart from the long-range nature of the interaction, this result is also consistent with the fact that the pairing gaps are largely enhanced by the resonant pair scattering [31,42,43].…”

Scale-Free Distribution of Oxygen Interstitial Wires in Optimum-Doped HgBa2CuO4+y

“…This scenario is consistent with the recent discovery that the space far from the oxygen interstitial atomic stripes in Hg1201 hosts segregated CDW ordered puddles [57]. The compelling evidence of scale invariant distribution of metallic wires in optimum doping Hg1201 supports the proposal that the system showing the superconducting high-critical temperature is in the proximity of a critical point for nanoscale phase separation near a Lifshitz transition in multi-band correlated electronic materials [64][65][66][67] in diborides [68], cuprates [69], organics [70,71], pressurized hydrides [72,73] showing high-order van Hove singularity [74,75], which could be further amplified by spin orbit coupling [76] due to internal electric field gradients driven by local charge segregation in oxygen-doped Hg1201. The compelling evidence of the nematic phase with scale-free distribution of atomic wires in mercury-based superconducting perovskites at optimum doping indicate the presence of critical opalescence [77] of atomic wires at a critical point involving local charge, spin [78,79], and electron-phonon interactions in two-dimensional superconductors [11,80].…”

Moir{é}-like superlattice generated van Hove singularities in strained CuO$_2$ double layer

“…The present results show that BSCCO is an intrinsic multi-band system where at high doping the chemical potential is close to a Lifshitz transition appearing at VHS at the metal to superconductor transition. Therefore, superconductivity in BSCCO is not a single-band unconventional superconducting phase but a multi-gap superconductor at a shape resonance described by Perali et al in cuprates 57,58 and appearing in diborides 59 , oxide interfaces 60 and in room temperature hydride superconductors 61 .…”