Dynamical spin response in cuprate superconductors from low-energy to high-energy

TL;DR

This paper investigates the dynamical spin response in cuprate superconductors across energy scales, revealing dispersive spin excitations, hour-glass-shaped dispersion in the superconducting state, and the role of spin self-energy effects in magnetic correlations.

Contribution

It introduces a kinetic energy driven mechanism to explicitly evaluate spin self-energy, explaining magnetic excitations and correlations in cuprates across doping levels.

Findings

Damped but well-defined dispersive spin excitations across doping.

Hour-glass-shaped dispersion of low-energy spin excitations in superconducting state.

High-energy spin excitations are doping-independent with similar spectral features in normal and superconducting states.

Abstract

Within the framework of the kinetic energy driven superconducting mechanism, the dynamical spin response of cuprate superconductors is studied from low-energy to high-energy. The spin self-energy is evaluated explicitly in terms of the collective charge carrier modes in the particle-hole and particle-particle channels, and employed to calculate the dynamical spin structure factor. Our results show the existence of damped but well-defined dispersive spin excitations in the whole doping phase diagram. In particular, the low-energy spin excitations in the superconducting-state have an hour-glass-shaped dispersion, with commensurate resonance that appears in the superconducting-state only, while the low-energy incommensurate spin fluctuations can persist into the normal-state. The high-energy spin excitations in the superconducting-state on the other hand retain roughly constant energy as a function of doping, with spectral weights and dispersion relations comparable to those in the corresponding normal-state. The theory also shows that the unusual magnetic correlations in cuprate superconductors can be ascribed purely to the spin self-energy effects which arise directly from the charge carrier-spin interaction in the kinetic energy of the system.