Momentum and doping dependence of spin excitations in electron-doped cuprate superconductors

TL;DR

This study investigates how spin excitations in electron-doped cuprate superconductors depend on momentum and doping, revealing significant differences from hole-doped counterparts and highlighting the role of high-energy excitations.

Contribution

It provides a detailed analysis of the doping and momentum dependence of spin excitations using the kinetic-energy-driven mechanism, emphasizing electron-hole asymmetry.

Findings

Low-energy spin excitation dispersion changes with doping

Hour-glass dispersion is absent in electron-doped cuprates

Resonance energy correlates with the superconducting gap

Abstract

Superconductivity in copper oxides emerges on doping holes or electrons into their Mott insulating parent compounds. The spin excitations are thought to be the mediating glue for the pairing in superconductivity. Here the momentum and doping dependence of the dynamical spin response in the electron-doped cuprate superconductors is studied based on the kinetic-energy-driven superconducting mechanism. It is shown that the dispersion of the low-energy spin excitations changes strongly upon electron doping, however, the hour-glass-shaped dispersion of the low-energy spin excitations appeared in the hole-doped side is absent in the electron-doped case due to the electron-hole asymmetry. In particular, the commensurate resonance appears in the superconducting-state with the resonance energy that correlates with the dome-shaped doping dependence of the superconducting gap. Moreover, the spectral weight and dispersion of the high-energy spin excitations in the superconducting-state are comparable with those in the corresponding normal-state, indicating that the high-energy spin excitations do not play an important part in the pair formation.