Spin Excitations in BaFe1.84Co0.16As2 Superconductor Observed by Inelastic Neutron Scattering

TL;DR

This study investigates spin excitations in the BaFe1.84Co0.16As2 superconductor using inelastic neutron scattering, revealing similarities and differences with cuprate superconductors, especially regarding the resonance peak's energy asymmetry.

Contribution

It provides detailed insights into the spin excitation spectrum of BaFe1.84Co0.16As2 and compares it with cuprates, highlighting unique features of the resonance peak.

Findings

Resonance peak is strongly tied to superconductivity.

Resonance occurs as an enhancement in the spin excitation spectrum.

The resonance peak is asymmetric in energy, unlike in cuprates.

Abstract

Superconductivity appears to compete against the spin-density-wave in Fe pnictides. However, optimally cobalt doped samples show a quasi-two-dimensional spin excitation centered at the (0.5, 0.5, L) wavevector, "the spin resonance peak", that is strongly tied to the onset of superconductivity. By inelastic neutron scattering on single crystals we show the similarities and differences of the spin excitations in BaFe1.84Co0.16As2, with respect to the spin excitations in the high-temperature superconducting cuprates. As in the cuprates the resonance occurs as an enhancement to a part of the spin excitation spectrum which extends to higher energy transfer and higher temperature. However, unlike in the cuprates, the resonance peak in this compound is asymmetric in energy.