The influence of topological phase transition on the superfluid density of overdoped copper oxides

• Published in: Physical chemistry chemical physics : PCCP 2017-08, Vol.19 (33), p.21964-21969
• Main Authors: Shaginyan, V R, Stephanovich, V A, Msezane, A Z, Japaridze, G S, Popov, K G
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c7cp02720f

We show that a quantum phase transition, generating flat bands and altering Fermi surface topology, is a primary reason for the exotic behavior of the overdoped high-temperature superconductors represented by La Sr CuO , whose superconductivity features differ from what is predicted by the classical Bardeen-Cooper-Schrieffer theory. This observation can open avenues for chemical preparation of high-T materials. We demonstrate that (1) at temperature T = 0, the superfluid density n turns out to be considerably smaller than the total electron density; (2) the critical temperature T is controlled by n rather than by doping, and is a linear function of the n ; (3) at T > T the resistivity ρ(T) varies linearly with temperature, ρ(T) ∝ αT, where α diminishes with T → 0, whereas in the normal (non superconducting) region induced by overdoping, T = 0, and ρ(T) ∝ T . Our results are in good agreement with recent experimental observations.