Microscopic Bardeen-Cooper-Schrieffer formulation of the critical temperature of multilayer copper-oxide superconductors

Abstract

We study superconductivity in multilayer copper oxides, in the frame of a realistic microscopic formulation. Solving the full temperature dependent BCS gap equations, we obtain a maximum in the transition temperature Tc for M=3 or 4 CuO2 layers in the unit cell for appropriate values of the interlayer tunneling (negative pair tunneling), and via the consideration of the doping imbalance between the inner and outer layers. This is the ubiquitous experimental result for Ca intercalated copper oxides, as opposed to other intercalating elements. Further, using a restricted set of parameters, we obtain an exact fit of Tc(M=1-4) for five different Ca intercalated homologuous copper oxide families.

Variational wavefunction for multi-species spinful fermionic superfluids and superconductors

“…In table 1 we show the ground state energy, as a function of V 1 = V 2 and V 0 , and the gap symmetry. These states Ψ have d x 2 −y 2 -wave superconducting gaps (the gap symmetry is due to the V i,q used [12]), for moderate values of V 0 , as shown in the table. In each quadrant, the lines marked 1 and 2 are the Fermi surfaces for species 1 and 2, respectively.…”

“…This problem is relevant for many different fermionic systems such as quark matter [4], nuclei [5], neutron stars [5], superconducting grains [6], cold atoms [7], graphene [8,9], APt 3 P (A=Sr,Ca,La) [10], and high-temperature superconductors, i.e. both copper oxides [11][12][13] and iron pnictides [14]. E.g.…”

“…The relevance of the BCS states to the calculation of T c for the multilayer copper oxide superconductors [12] provided a motivation for this work, in an effort to consider relevant pairing correlations, beyond the standard BCS ones.…”

Correlation-induced Suppression of Bilayer Splitting in High-T c Cuprates: A Variational Cluster Approach

“…There have been several explanations for this phenomenon. Among them, one could mention interlayer interactions, charge imbalance, or quantum tunneling of Cooper pairs [ 2 – 4 ].…”