Magnetic excitations in La-based cuprate superconductors: Slave-boson mean-field analysis of the two-dimensional t−J model

Abstract

Motivated by recent inelastic neutron scattering experiments up to a high-energy region for La-based cuprates, we compute (q,ω) maps of the imaginary part of the dynamical magnetic susceptibility χ(q,ω) in the slave-boson mean-field approximation to the two-dimensional t−J model. While the strong spectral weight appears at incommensurate positions, namely, at q≠Q≡(π,π), for low energy, the incommensurate signals disperse with increasing ω and finally merge into a commensurate signal at a particular energy ω=ωQ. These features are seen in both the d-wave pairing state and the normal state. In particular, the incommensurate signals below ωQ in the normal state are due to the Fermi surface geometry, which we expect for La-based cuprates because of a tendency to d-wave type Fermi surface deformations. Above ωQ, strong signals appear to trace an upward dispersion especially for a low doping rate in the d-wave pairing state while typically broad spectral weight is obtained around q=Q in the normal state. Salient features of magnetic excitations in La-based cuprates are thus naturally captured in terms of particle-hole excitations. Global understanding of magnetic excitations in high-Tc cuprates is discussed through a comparison with magnetic excitations in YBa2Cu3Oy.

Source-reported materials — not catalogue approval

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