Electronic Origin of the Inhomogeneous Pairing Interaction in the High- T _c Superconductor Bi ₂ Sr ₂ CaCu ₂ O _8+δ

Abstract

Identifying the mechanism of superconductivity in the high-temperature cuprate superconductors is one of the major outstanding problems in physics. We report local measurements of the onset of superconducting pairing in the high-transition temperature (Tc) superconductor Bi2Sr2CaCu2O8+delta using a lattice-tracking spectroscopy technique with a scanning tunneling microscope. We can determine the temperature dependence of the pairing energy gaps, the electronic excitations in the absence of pairing, and the effect of the local coupling of electrons to bosonic excitations. Our measurements reveal that the strength of pairing is determined by the unusual electronic excitations of the normal state, suggesting that strong electron-electron interactions rather than low-energy (<0.1 volts) electron-boson interactions are responsible for superconductivity in the cuprates.

Determinant quantum Monte Carlo study of the two-dimensional single-band Hubbard-Holstein model

“…Although the identity of this mode (be it an electronic collective mode or one or more phonon modes) remains controversial, the appearance of the dispersion renormalizations at multiple energy scales ranging from 10 -110 meV strongly suggests coupling to a spectrum of oxygen phonons. [18][19][20][21][22][23] These electronic renormalizations have analogous features in the density of states as probed by scanning tunnelling microscopy [24][25][26][27][28][29][30][31] as well as in the optical properties of the cuprates. 32,33 Moving beyond the cuprates, strong e-ph and electronelectron (e-e ) interactions also are believed to be operative in a number of other systems.…”

Imaging nanoscale Fermi-surface variations in an inhomogeneous superconductor

“…Perhaps the clearest examples consist of recent STM results showing that the gap closing temperature varies spatially, scaling with local gap size 5 , and that both are correlated with higher temperature electronic structure 22 . These results are unsurprising given the local FS variations we report here.…”

Development of Spatial Inhomogeneity of Internal Magnetic Field Above Tc in Bi2Sr2Ca1−xYxCu2O8+δ Observed by Longitudinal-Field Muon Spin Relaxation

“…8,9,[14][15][16][17][18][19][20][21][22][23] Supposed that a few nanoscale SC domains are developed in the CuO 2 plane, magnetic fluxes are expelled from the nanoscale SC domains due to the Meissner effect. In this case, the internal magnetic field parallel to the initial muon polarization inside the SC domains decrease and the bending of the magnetic fluxes generates the internal magnetic field perpendicular to the initial J. Phys.…”

“…[14][15][16] The recent study of the scanning tunneling microscopy (STM) in BSCCO has suggested that pairing gaps tend to nucleate in nanoscale regions at temperatures far above T c . [17][18][19] Moreover, both the linear diamagnetic response in the magnetization measurements in Tl 2 Ba 2 CuO 6+δ , 20,21 the hysteresis in the low-field magnetization curve in LSCO, 22 the enhancement of the relaxation rate in the transverse-field (TF) muon-spin-relaxation (µSR) measurements in LSCO and YBCO 23 and the result of high-frequency conductivity measurements in LSCO [8][9][10] have also suggested the presence of small SC domains at temperatures above T c .…”