Optical determination of the relation between the electron-boson coupling function and the critical temperature in high-Tccuprates

Abstract

We take advantage of the connection between the free-carrier optical conductivity and the glue function in the normal state, to reconstruct from the infrared optical conductivity the glue spectrum of ten different high-T c cuprates revealing a robust peak in the 50-60 meV range and a broad continuum at higher energies for all measured charge-carrier concentrations and temperatures up to 290 K. We observe that the strong-coupling formalism accounts fully for the known strong temperature dependence of the optical spectra of the high-T c cuprates, except for strongly underdoped samples. We observe a correlation between the doping trend of the experimental glue spectra and the critical temperature. The data obtained on the overdoped side of the phase diagram conclusively exclude the electron-phonon coupling as the main source of superconducting pairing.

Hidden magnetic excitation in the pseudogap phase of a high-Tc superconductor

“…The hitherto unobserved excitation found here at the same energy as the resonance, but up to higher temperature and all the way to q = 0, is a new candidate for the mysterious electron-boson-interaction features observed by photoemission [7], optical spectroscopy [8,9] and scanning tunneling spectroscopy [10]. At q AF , the strength of the excitation is comparable to that of the resonance (in Hg1201 (Fig.…”

“…The mode's intensity rises below the same temperature T * and its dispersion is weak, as expected for an Ising-like order parameter [6]. Its energy of 52-56 meV and its enormous integrated spectral weight render it a new candidate for the hitherto unexplained ubiquitous electron-boson coupling features observed in spectroscopic studies [7][8][9][10].Inelastic neutron scattering (INS) is the most direct probe of magnetic excitations in solids. In the present work, we employed both spin-polarized and unpolarized INS measurements.…”

Strong-coupling analysis of scanning tunneling spectra in Bi2Sr2Ca2CuBerthod1, Fasano2, Maggio-Aprile3 et al. 2013Phys. Rev. B

“…34 As the dip feature is stronger in Bi-2223 than in Bi-2212, a larger value may be expected for the three-layer compound. Indeed, the average renormalization in the normal state of Bi-2223 at optimal doping was estimated by fitting a model with a bosonic spectrum to optical data, 43 and leads to the values 2.18 and 1.75, depending on whether the full bosonic spectrum or its low-energy part is taken into account, respectively. In the normal state, but at the nodal point, a renormalization decreasing from 0.8 to 0.55 as a function of increasing hole doping was measured in Bi-2212 at 120 K. 83 Our nodal values for Bi-2223 in the normal state with s = 25 meV draw a similar trend, decreasing from 0.8 to 0.5 with decreasing gap size.…”

“…This interaction affects the one-electron spectra and is observable in the single-electron spectroscopies. Although the strength of this interaction has been a matter of controversy, 31,32 there is evidence that peculiar signatures observed in photoemission, [33][34][35][36] tunneling, [37][38][39][40][41] and optical conductivity 42,43 result from this interaction. Yet, a firm consensus has not been reached: Optical phonons often exist in the cuprates at similar energies, and distinguishing the effects of the two kinds of excitations has proven difficult.…”

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

“…[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. These include the quasi-1D edge-shared cuprates, 34 the manganites, [35][36][37] , the fullerenes, [38][39][40][41] and the rare-earth nickelates.…”