Unconventional energetics of the pseudogap state and superconducting state in high-Tccuprates

Abstract

Insight into the nature of the pairing of charge carriers in high-T c superconductors may be provided by a systematic investigation of the condensation energy. In this work we report on studies of the electronic kinetic energy across the complex phase diagram of these materials. The c-axis component of the electronic kinetic energy ͑determined from an analysis of the optical constants͒ is shown to be reduced below T c , primarily in those compounds in which the superconducting transition at T c is preceded by the formation of the partial gap in the density of states ͑pseudogap͒ at T*ϾT c . An examination of the doping dependence of the infrared conductivity in conjunction with the results of photoemission spectroscopy suggests that the lowering of the kinetic energy is a property of the electronic states close to the intersection of the two-dimensional Fermi surface with the boundary of the Brillouin zone. We contrast the c-axis results with the energetics associated with the nodal quasiparticles probed through the in-plane conductivity. component of their effective mass tensor. The second contribution 1,r reg () ͑usually referred to as the ''regular'' compo-nent͒ is defined at Ͼ0 and is associated with the response

Electrodynamics of the nodal metal state in weakly doped high-Tccuprates

“…38,39 New results reported here for even lower dopings: y = 6.50 and 6.55 ( Fig. 8) uncover several unexpected features.…”

Electron dynamics inNd1.85Ce0.15CuO4+Singley1, Basov2, Kurahashi3 et al. 2001Phys. Rev. BSelf Cite849680View full textAdd to dashboardCite

“…The incoherent conductivity which drives the source of s to higher energies has been linked to the normal state pseudogap. 75 For technical reasons we were not able to observe a pseudogap in the c-axis conductivity of NCCO. 83 However, the extremely small values of 1 () along with the absence of any obvious Drude peak in the interlayer conductivity is consistent with strongly incoherent transport.…”

Superconductivity in mesoscopic high-Tc superconducting particles

“…Noteworthy, the more recent data for YBCO 34 give closed estimate m ≈ 8 − 9m e under the assumption of a twice band mass enhancement due to electron correlations: m b = 2m e . Such estimate m ≈ 10m e is also in an agreement with theoretical evaluations 35,36 for an effective electron mass in YBCO.…”