Particle-hole asymmetry in the dynamical spin and charge responses of corner-shared 1D cuprates

Abstract

Although many experiments imply that oxygen orbitals play an essential role in the high-temperature superconducting cuprates, their precise role in collective spin and charge excitations and superconductivity is not yet fully understood. Here, we study the doping-dependent dynamical spin and charge structure factors of single and multi-orbital (pd) models for doped one-dimensional corner-shared spin-chain cuprates using several numerically exact methods. In doing so, we determine the orbital composition of the collective spin and charge excitations of cuprates, with important implications for our understanding of these materials. For example, we observe a particle-hole asymmetry in the orbital-resolved charge excitations, which is directly relevant to resonant inelastic x-ray scattering experiments and not captured by the single-band Hubbard model. Our results imply that one must explicitly include the oxygen degrees of freedom in order to fully understand some experimental observations on cuprate materials.

One- and two-particle properties of the weakly interacting two-dimensional Hubbard model in proximity to the van Hove singularity

“…Such splitting is similar to what has been observed at stronger coupling strengths for charge excitations in 1D Hubbard chains due to the formation of a gap. [47] We note that multiple peaks only occur for densities near or below the van Hove point. Recent Raman experiments have suggested that the pseudogap phenomenon might terminate at the density associated with the Lifshitz point [48] which for a weakly coupled system coincides with the van Hove singularity.…”

Fast and scalable quantum Monte Carlo simulations of electron-phonon models

“…In particular, the broad class of determinant QMC (DQMC) methods have proven highly effective in helping to characterize various correlated phases that arise as a result of interactions [1]. Perhaps most notably, DQMC has enabled the study of electron-electron interactions in the repulsive Hubbard model, where Mott insulator physics, magnetic order, unconventional superconductivity, and various additional correlation effects have been observed [2][3][4][5][6][7][8][9][10]. The sign problem, however, has severely limited our ability to simulate systems absent particle-hole or other symmetries, giving rise to an effective computational cost that scales exponentially with system size and inverse temperature [11][12][13][14][15][16][17].…”

Suppressed superexchange interactions in the cuprates by bond-stretching oxygen phonons

“…We solve this model using exact diagonalization (ED) and determinant quantum Monte Carlo (DQMC), which provide numerically exact results on finite-size clusters. (Here, we can run DQMC simulations at comparatively low temperatures due to a mildler sign problem compared to 2D [53,54].) Focusing on half-filling, we find that the system has a narrow window of coupling strengths where it supports a q = π/a bond ordering.…”

“…(For details of the method, we refer the reader to Refs. [53] and [46].) We now include the individual atomic motion of each 2p x orbital along the chain direction.…”

“…Here, Ŝz i = γ Ŝz i,γ is the total spin operator for the unit cell [53]. For a spin 1/2 system like Sr 2 CuO 3 , the uniform magnetic susceptibility is frequently used by experimentalists to determine the value of the effective superexchange coupling J [55][56][57][58].…”