Related papers: An unusual isotope effect in a high-transition-tem…
Coupling between electrons and phonons (lattice vibrations) drives the formation of the electron pairs responsible for conventional superconductivity. The lack of direct evidence for electron-phonon coupling in the electron dynamics of the…
We review various isotope effects in the high-T_c cuprate superconductors to assess the role of the electron-phonon interaction in the basic physics of these materials. Of particular interest are the unconventional isotope effects on the…
We show that recent ARPES results on the "unusual" oxygen isotope shift in the real part of the self-energy in the optimally doped $Bi2212$ samples can be qualitatively (and semi-quantitatively) explained by the theory of the…
The recent discovery of superconductivity in oxypnictides with the critical temperature (TC) higher than McMillan limit of 39 K (the theoretical maximum predicted by Bardeen-Cooper-Schrieffer (BCS) theory) has generated great excitement.…
Looking for superconductors with higher transition temperature requires a guiding principle. In conventional superconductors, electrons pair up into Cooper pairs via the retarded attraction mediated by electron-phonon coupling.…
Based on recently proposed anti-ferromagnetic spin fluctuation exchange models for $d_{x^2-y^2}$-superconductors, we show that coupling to harmonic phonons {\it{cannot}} account for the observed isotope effect in the cuprate high-$T_c$…
Superconductivity in high-Tc cuprates is unconventional and there is a growing acceptance that carrier pairing in these strongly correlated electronic materials is mediated mainly by bosons of electronic origin rather than the phonons.…
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…
The weak-coupling quantum phase diagrams of the one-dimensional (1D) Holstein-Hubbard and Peierls-Hubbard models are computed near half-filling, using a multi-step renormalization group technique. If strong enough, the electron-phonon…
We have measured the near-normal reflectance of Tl2Ba2CaCu2O8 (Tl2212) for energies from 0.1 to 4.0 eV at room temperature and used a Kramers-Kronig analysis to find the complex, frequency dependent dielectric function, from which the…
Formation of electron pairs is essential to superconductivity. For conventional superconductors, tunnelling spectroscopy has established that pairing is mediated by bosonic modes (phonons); a peak in the second derivative of tunnel current…
The elementary CuO2 plane sustaining cuprate high-temperature superconductivity occurs typically at the base of a periodic array of edge-sharing CuO5 pyramids. Virtual transitions of electrons between adjacent planar Cu and O atoms,…
Investigation of isotope effects on superconducting transition temperature (Tc) is one of the useful methods to examine whether electron-phonon interaction is essential for pairing mechanisms. The layered BiCh2-based (Ch: S, Se)…
The effect of the 16O-->18O substitution on the superconducting transition temperatures Tc of NaxCoO2.yH2O has been studied for several sets of samples. Each set has two kinds of samples, one with the oxygen sites in the CoO2 layers filled…
In this paper, I study the oxygen isotope effect (OIE) in cuprates. I introduce a simple model that can explain experiments both qualitatively and quantitatively. In this theory, isotope substitution only affects the superfluid density, but…
Electron-boson coupling plays a key role in superconductivity for many systems. However, in copper-based high-temperature ($T_c$) superconductors, its relation to superconductivity remains controversial despite strong spectroscopic…
TThe isotope effect is a powerful probe of electron-phonon interactions in solid-state systems, offering key insights into how atomic mass influences emergent quantum states. Here, the impact of oxygen isotope substitution ($^{16}{\rm…
We investigate the effect of isotope substitution on the electron-phonon interaction in the multi-band superconductor MgB2 using tunable laser based Angle Resolved Photoemission Spectroscopy. The kink structure around 70 meV in the $\sigma$…
The fundamental mechanism that gives rise to high-transition-temperature (high-Tc) superconductivity in the copper oxide materials has been debated since the discovery of the phenomenon. Recent work has focussed on a sharp 'kink' in the…
It is shown that the translation-invariant bipolaron theory of superconductivity can explain the dependence of the isotope coefficient in high-temperature superconductors on the critical temperature of a superconducting transition: in the…