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A comprehensive angle-resolved photoemission spectroscopy study of the band structure in single-layer cuprates is presented with the aim of uncovering universal trends across different materials. Five different hole- and electron-overdoped cuprate superconductors (${\mathrm{La}}_{1.59}{\mathrm{Eu}}_{0.2}{\mathrm{Sr}}_{0.21}{\mathrm{CuO}}_{4}$, ${\mathrm{La}}_{1.77}{\mathrm{Sr}}_{0.23}{\mathrm{CuO}}_{4}$, ${\mathrm{Bi}}_{1.74}{\mathrm{Pb}}_{0.38}{\mathrm{Sr}}_{1.88}{\mathrm{CuO}}_{6+{\delta}}$, ${\mathrm{Tl}}_{2}{\mathrm{Ba}}_{2}{\mathrm{CuO}}_{6+{\delta}}$, and ${\mathrm{Pr}}_{1.15}{\mathrm{La}}_{0.7}{\mathrm{Ce}}_{0.15}{\mathrm{CuO}}_{4}$) have been studied with special focus on the bands with a predominately $d$-orbital character. Using a light polarization analysis, the ${e}_{g}$ and ${t}_{2g}$ bands are identified across these materials. A clear correlation between the ${d}_{3{z}^{2}{-}{r}^{2}}$ band energy and the apical oxygen distance ${d}_{\mathrm{A}}$ is demonstrated. Moreover, the compound dependence of the ${d}_{{x}^{2}{-}{y}^{2}}$ band bottom and the ${t}_{2g}$ band top is revealed. A direct comparison to density functional theory (DFT) calculations employing hybrid exchange-correlation functionals demonstrates excellent agreement. We thus conclude that the DFT methodology can be used to describe the global band structure of overdoped single-layer cuprates on both the hole- and electron-doped side." name="description" />

We present a resonant inelastic x-ray scattering (RIXS) study of spin and charge excitations in overdoped La1.77Sr0.23CuO4 along two high-symmetry directions. The line shape of these excitations is analyzed and they are shown to be highly overdamped. Their spectral weight and damping are found to be strongly momentum dependent. Qualitative agreement between these observations and a calculated random-phase approximation susceptibility is obtained for this overdoped compound, implying that a significant contribution to the RIXS signal stems from a continuum of charge excitations. Furthermore, this suggests that the spin excitations in the overdoped regime can be captured qualitatively by an itinerant picture. Our calculations also predict a low-energy spin-excitation branch to exist along the nodal direction near the zone center. With the energy resolution of the present experiment, this branch is not resolvable, but we show that the next generation of high-resolution spectrometers will be able to test this prediction.

Nodal angle-resolved photoemission spectra taken on overdoped La1.77Sr0.23CuO4 are presented and analyzed. It is proven that the low-energy excitations are true Landau Fermi-liquid quasiparticles. We show that momentum and energy distribution curves can be analyzed self-consistently without quantitative knowledge of the bare band dispersion. Finally, by imposing Kramers-Kronig consistency on the self-energy Sigma, insight into the quasiparticle residue is gained. We conclude by comparing our results to quasiparticle properties extracted from thermodynamic, magnetoresistance, and high-field quantum oscillation experiments on overdoped Tl2Ba2CuO6+delta.

We use small-angle neutron scattering to study the superconducting vortex lattice in La2−xSrxCuO4 as a function of doping and magnetic field. We show that near optimally doping the vortex lattice coordination and the superconducting coherence length ξ are controlled by a Van Hove singularity crossing the Fermi level near the Brillouin zone boundary. The vortex lattice properties change dramatically as a spin-density-wave instability is approached upon underdoping. The Bragg glass paradigm provides a good description of this regime and suggests that spin-density-wave order acts as a source of disorder on the vortex lattice.

We use inelastic neutron scattering to study the temperature dependence of the low-energy spin excitations in single crystals of superconducting FeTe${}_{0.6}$Se${}_{0.4}$ (${T}_{c}=14$ K). In the low-temperature superconducting state, the imaginary part of the dynamic susceptibility at the electron and hole Fermi-surfaces nesting wave vector $Q=(0.5,0.5)$, ${\ensuremath{\chi}}^{\ensuremath{'}\ensuremath{'}}(Q,\ensuremath{\omega})$, has a small spin gap, a two-dimensional neutron spin resonance above the spin gap, and increases linearly with increasing $\ensuremath{\hbar}\ensuremath{\omega}$ for energies above the resonance. While the intensity of the resonance decreases like an order parameter with increasing temperature and disappears at temperature slightly above ${T}_{c}$, the energy of the mode is weakly temperature dependent and vanishes concurrently above ${T}_{c}$. This suggests that in spite of its similarities with the resonance in electron-doped superconducting BaFe${}_{2\ensuremath{-}x}$(Co,Ni)${}_{x}$As${}_{2}$, the mode in FeTe${}_{0.6}$Se${}_{0.4}$ is not directly associated with the superconducting electronic gap.

U.S. DOE BES[DE-FG02-05ER46202]; U.S. DOE, Division of Scientific User Facilities; CAS; U.S. DOE[DE-AC02-06CH11357]; DOE BES EPSCoR[DE-FG02-08ER46528]