Anisotropic softening of collective charge modes in the vicinity of critical doping in a doped Mott insulator

Abstract

Momentum resolved inelastic resonant x-ray scattering is used to map the evolution of charge excitations over a large range of energies, momenta and doping levels in the electron doped Mott insulator class Nd${}_{2-x}$Ce${}_x$CuO${}_4$. As the doping induced AFM-SC (antiferromagnetic-superconducting) transition is approached, we observe an anisotropic softening of collective charge modes over a large energy scale along the Gamma to (π,π)-direction, whereas the modes exhibit broadening ($\sim$ 1 eV) with relatively little softening along Gamma to (π,0) with respect to the parent Mott insulator (x=0). Our study indicates a systematic collapse of the gap consistent with the scenario that the system dopes uniformly with electrons even though the softening of the modes involves an unusually large energy scale.

5 pages + 5 Figures

References in corpus (2)

• Momentum Dependence of Charge Excitations in the Electron-Doped Superconductor Nd1.85Ce0.15CuO4: a RIXS Study
• Mott gap excitations in twin-free YBa2Cu3O7-d (Tc = 93 K) studied by RIXS

Cited by in corpus (7)

• Intermediate Coupling Model of the Cuprates
• Failure of t-J models in describing doping evolution of spectral weight in x-ray scattering, optical and photoemission spectra of the cuprates
• Renormalization of f-levels away from the Fermi energy in electron excitation spectroscopies: Density functional results of Nd${}_{2-x}$Ce${}_x$CuO${}_4$
• Experimental signatures of phase interference and sub-femtosecond time dynamics on the incident energy axis of resonant inelastic X-ray scattering
• Lindhard and RPA susceptibility computations in extended momentum space in electron doped cuprates
• Coexisting pseudogap, charge transfer gap, and Mott gap energy scales in the resonant inelastic x-ray scattering spectra of electron-doped cuprates
• Post-growth annealing effects on charge and spin excitations in Nd${}_{2-x}$Ce${}_x$CuO${}_4$