Evolution of Superconducting-Transition Temperature with Superfluid Density and Conductivity in Pressurized Cuprate Superconductors

Abstract

What factors fundamentally determine the value of superconducting transition temperature T c in high temperature superconductors has been the subject of intense debate. Following the establishment of an empirical law known as Homes’ law, there is a growing consensus in the community that the T c value of the cuprate superconductors is closely linked to the superfluid density (ρ s) of its ground state and the conductivity (σ) of its normal state. However, all the data supporting this empirical law (ρ s = AσT c) have been obtained from the ambient-pressure superconductors. In this study, we present the first high-pressure results about the connection of the quantities of ρ s and σ with T c, through the studies on the Bi1.74Pb0.38Sr1.88CuO6+δ and Bi2Sr2CaCu2O8+δ , in which the value of their high-pressure resistivity (ρ = 1/σ) is achieved by adopting our newly established method, while the quantity of ρ s is extracted using Homes’ law. We highlight that the T c values are strongly linked to the joint response factors of magnetic field and electric field, i.e., ρ s and σ, respectively, implying that the physics determining T c is governed by the intrinsic electromagnetic fields of the system.