Spin gap and magnetic resonance in superconducting BaFe1.9Ni0.1As2

Shiliang Li; Ying Chen; Sung Chang; Jeffrey W. Lynn; Linjun Li; Yongkang Luo; Guanghan Cao; Zhu’an Xu; Pengcheng Dai

doi:10.1103/PhysRevB.79.174527

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Spin gap and magnetic resonance in superconducting BaFe1.9Ni0.1As2

Shiliang Li, Ying Chen, Sung Chang, Jeffrey W. Lynn, Linjun Li, Yongkang Luo, Guanghan Cao, Zhu’an Xu, Pengcheng Dai

DOI 10.1103/PhysRevB.79.174527 · Physical Review B

T1

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Abstract

We use neutron spectroscopy to determine the nature of the magnetic excitations in superconducting BaFe1.9Ni0.1As2(Tc=20 K). Above Tc the excitations are gapless and centered at the commensurate antiferromagnetic wave vector of the parent compound, while the intensity exhibits a sinusoidal modulation along the c axis. As the superconducting state is entered a spin gap gradually opens, whose magnitude tracks the T dependence of the superconducting gap as observed by angle-resolved photoemission. Both the spin-gap and magnetic-resonance energies are temperature and wave-vector dependent, but their ratio is the same within uncertainties. These results suggest that the spin resonance is a singlet-triplet excitation related to electron pairing and superconductivity.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
BaFe1.9Ni0.1As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	20	Pressure not reported	onset
BaFe1.84Co0.16As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	22	Pressure not reported	unknown