Dispersion of the superconducting spin resonance in underdoped and antiferromagnetic Ba(Fe1-xCox)2As2

TL;DR

This study investigates how the magnetic resonance in underdoped Ba(Fe1-xCox)2As2 varies along the c-axis, revealing that antiferromagnetic order influences the dispersion of the resonance in superconducting iron pnictides.

Contribution

It demonstrates that the resonance dispersion in underdoped Ba(Fe1-xCox)2As2 is linked to interlayer spin correlations associated with antiferromagnetic order, contrasting with optimally doped samples.

Findings

Resonance exhibits significant dispersion along the c-axis in underdoped samples.

Dispersion is weaker in optimally doped samples without AFM order.

Interlayer spin correlations contribute to the resonance dispersion.

Abstract

Inelastic neutron scattering measurements have been performed on underdoped Ba(Fe1-xCox)2As2 (x = 4.7%) where superconductivity and long-range antiferromagnetic (AFM) order coexist. The broad magnetic spectrum found in the normal state develops into a magnetic resonance feature below TC that has appreciable dispersion along c-axis with a bandwidth of 3-4 meV. This is in contrast to the optimally doped x = 8.0% composition, with no long-range AFM order, where the resonance exhibits a much weaker dispersion [see Lumsden et al. Phys. Rev. Lett. 102, 107005 (2009)]. The results suggest that the resonance dispersion arises from interlayer spin correlations present in the AFM ordered state.