Feshbach Shape Resonance in Multiband Superconductivity in Heterostructures

Abstract

We report experimental data showing the Feshbach shape resonance in the electron Van Hove-Lifshits feature for the change of Fermi surface dimensionality in the electronic energy spectrum in one of the subbands. In this heterostructure at atomic limit the multiband superconductivity is in the clean limit because the disparity and negligible overlap between electron wavefunctions in different subbands suppresses the single electron interband impurity scattering rate. The emerging scenario from these 2 experimental data suggests that the Feshbach shape resonance could be the mechanism for high T c in particular nanostructured architectures.

Shape Resonance at a Lifshitz Transition for High Temperature Superconductivity in Multiband Superconductors

“…i) boron honeycomb layers separated by Al, Mg or Sc layers, (called diborides) [33][34][35][36][37][38] ii) honeycomb graphene layers intercalated by different spacer layers (called intercalated graphite) [39] iii) iron fcc layers intercalated by many different types of spacers (called pnictides or iron-based superconductors) [40][41][42][43][44][45][46][47], iv) superlattices of carbon nanotubes [48] In fact all these systems show similar features [49][50][51][52] being multilayers near a Lifshitz transition. In this 2.5 electronic phase transition [53][54][55][56][57][58][59][60] the system is in the verge of a first order phase transition, with the possible appearance of a tricritical point.…”

“…Multiband superconductivity is now emerging as a fundamental common feature in the Fermiology of cuprates [65][66][67][68][69][70][71][72][73][74][75], diborides [36] and pnictides [45][46][47] where the chemical potential is tuned in the proximity of a quantum critical Lifshitz transition. There is now growing agreement that the critical temperature appears by a fine tuning of the chemical potential near a Lifshitz transition [76][77][78][79] where the superconductivity involve the change of the symmetry of the Fermi surface and of the superconducting condensate.…”

Special Issue: Abstracts From the 2008 Issol Meeting

“…We show that by selecting particular nanoscale architectures and driving the system close a to a quantum critical point it is possible to realize a particular superfluid that is able to avoid temperature de-coherence effects. We show that a particular quantum critical point can be reached at a critical values of (a) density, (b) disorder, (c) chemical pressure and (d) temperature (Fratini et al 2008) where the quantum many body Feshbach resonance or shape resonance (Bianconi 2005 for molecular association and dissociation processes is actually effective to give a macroscopic quantum coherent phase that avoids the temperature quantum de-coherence effects. We show that the proximity to a particular quantum critical point is related with the emergence of the Feshbach resonance.…”

Two-Bands Superconductivity with Intra- and Interband Pairing for Synthetic Superlattices

“…In fact where the chemical potential is tuned near an electronic topological transition the high temperature superconductivity has been associated with quantum interference effects, called shape resonances, in the interband pairing terms since 1993 [4,5].…”