Resonant Inelastic X-ray Scattering Study of Electron-Exciton Coupling in High-Tc Cuprates

Abstract

Explaining the mechanism of superconductivity in the high-$T_c$ cuprates requires an understanding of what causes electrons to form Cooper pairs. Pairing can be mediated by phonons, the screened Coulomb force, spin or charge fluctuations, excitons, or by a combination of these. An excitonic pairing mechanism has been postulated, but experimental evidence for coupling between conduction electrons and excitons in the cuprates is sporadic. Here we use resonant inelastic x-ray scattering (RIXS) to monitor the temperature dependence of the $\underline{d}d$ exciton spectrum of Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8-x}$ (Bi-2212) crystals with different charge carrier concentrations. We observe a significant change of the $\underline{d}d$ exciton spectra when the materials pass from the normal state into the superconductor state. Our observations show that the $\underline{d}d$ excitons start to shift up (down) in the overdoped (underdoped) sample when the material enters the superconducting phase. We attribute the superconductivity-induced effect and its sign-reversal from underdoped to overdoped to the exchange coupling of the site of the $\underline{d}d$ exciton to the surrounding copper spins.

arXiv comment13 pages, 10 figures

References in corpus (32)

• A Common Thread: the pairing interaction for the unconventional superconductors
• The Hubbard Model
• The effect of collective spin-1 excitations on electronic spectra in high-Tc superconductors
• Phenomenological Models for the Gap Anisotropy of Bi-2212 as Measured by ARPES
• Superconductivity in the Hubbard model and its interplay with charge stripes and next-nearest hopping t'
• Energy and symmetry of $dd$ excitations in undoped layered cuprates measured by Cu $L_3$ resonant inelastic x-ray scattering
• Revealing the high-energy electronic excitations underlying the onset of high-temperature superconductivity in cuprates
• Electronic Collective Modes and Superconductivity in Layered Conductors
• Energetic balance of the superconducting transition across the BCS-Bose E instein crossover in the attractive Hubbard model
• High-energy magnetic excitations in Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$: Towards a unified description of the electronic and magnetic degrees of freedom in the cuprates
• Abrupt transition in quasiparticle dynamics at optimal doping in a cuprate superconductor system
• Energetics of superconductivity in the two dimensional Hubbard model
• The Superconducting Condensation Energy and an Antiferromagnetic Exchange Based Pairing Mechanism
• Kinetic energy change with doping upon superfluid condensation in high temperature superconductors
• Doping Dependence of the Redistribution of Optical Spectral Weight in Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$
• An organizing principle for two-dimensional strongly correlated superconductivity
• Why holes are not like electrons: A microscopic analysis of the differences between holes and electrons in condensed matter
• Heavy anion solvation of polarity fluctuations in Pnictides
• Optical Conductivity of the t-J model within Cluster Dynamical Mean Field Theory
• Large Bi-2212 single crystal growth by the floating-zone technique
• Charge-orbital-lattice coupling effects in the dd-excitation profile of one dimensional cuprates
• Crossover of Charge Fluctuations across the Strange Metal Phase Diagram
• Bosonic Spectral Function and The Electron-Phonon Interaction in HTSC Cuprates
• Temperature-dependent ellipsometry measurements of partial Coulomb energy in superconducting cuprates
• Magnetic excitations and phonons simultaneously studied by resonant inelastic x-ray scattering in optimally doped Bi${}_{1.5}$Pb${}_{0.55}$Sr${}_{1.6}$La${}_{0.4}$CuO${}_{6+\delta }$
• Itinerant effects and enhanced magnetic interactions in Bi-based multilayer cuprates
• Superconductivity-induced spectral weight transfer due to quantum geometry
• d_{3z^2-r^2} Orbital in high-Tc cuprates: Excitonic spectrum, metal-insulator phase diagram, optical conductivity and orbital character of doped holes
• A determination of the pairing interaction in the high Tc cuprate superconductor Tl2Ba2CaCu2O8 (Tl2212)
• Evidence for Kosterlitz-Thouless and 3D-xy critical behavior in Bi2212
• Orbital Symmetry and Orbital Excitations in High-$T_c$ Superconductors
• Quantum-geometry-induced intrinsic optical anomaly in multiorbital superconductors

Cited by in corpus (5)

• Reconciling scaling of the optical conductivity of cuprate superconductors with Planckian resistivity and specific heat
• Collective nature of orbital excitations in layered cuprates in the absence of apical oxygens
• Dynamics of non-thermal states in optimally-doped $B{i}_{2}S{r}_{2}C{a}_{0.92}{Y}_{0.08}C{u}_2{O}_{8+\delta }$ revealed by mid-infrared three-pulse spectroscopy
• Ligand Field Exciton Annihilation in Bulk CrCl3
• Evolution of orbital excitations from insulating to superconducting MgTi${}_2$O${}_4$ films