Slave Boson Approach to The Neutron Scattering in YBCO Superconductors

TL;DR

This paper uses slave-boson theory to analyze the magnetic resonance in YBCO superconductors, revealing how it evolves with doping and explaining incommensurate responses through dynamic nesting effects.

Contribution

It applies slave-boson theory to the t-t'-J-model to explain the doping-dependent evolution of the neutron scattering resonance in YBCO superconductors.

Findings

Resonance appears as a collective spin fluctuation in the d-wave SC state.

Resonance energy decreases and broadens with reduced hole filling.

Incommensurate response emerges below the resonance energy due to dynamic nesting.

Abstract

The evolution of the so-called `41meV resonance' in the magnetic response of YBCO cuprates is studied with slave-boson theory for the t-t'-J-model. The resonance appears as a collective spin fluctuation in the d-wave superconducting (SC) state. It is undamped at optimal doping due to a threshold in the excitation energies of particle--hole pairs with relative wave vector (pi,pi). When hole filling is reduced, the resonance moves to lower energies and broadens. Below the resonance energy we find a crossover to an incommensurate response in agreement with a recent experiment on YBa_2CU_3O_6.6. We show that dynamic nesting in the d-wave SC state causes this effect.