Abstract
We use inelastic neutron scattering to study the energy and wave-vector dependence of the superconductivity-induced resonance in hole-doped Ba0.67K0.33(Fe1-xCox)2As2 (x=0 and 0.08 with Tc≈37 and 28 K, respectively). In previous work on electron-doped Ba(Fe0.963Ni0.037)2As2 (TN=26 K and Tc=17 K), the resonance is found to peak sharply at the antiferromagnetic (AF) ordering wave vector QAF along the longitudinal direction, but disperses upwards away from QAF along the transverse direction [Kim, Phys. Rev. Lett. 110, 177002 (2013)PRLTAO0031-900710.1103/PhysRevLett.110.177002]. For hole-doped x=0 and 0.08 without AF order, we find that the resonance displays a ringlike upward dispersion away from QAF along both the longitudinal and transverse directions. By comparing these results with calculations using the random phase approximation, we conclude that the dispersive resonance is a direct signature of isotropic superconducting gaps arising from nested hole-electron Fermi surfaces.
Original language | English |
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Article number | 060502 |
Journal | Physical Review B |
Volume | 98 |
Issue number | 6 |
DOIs | |
State | Published - Aug 30 2018 |
Funding
The neutron scattering work at Rice University was supported by US NSF Grant No. DMR-1700081 (P.D.). The single-crystal synthesis work was supported by the Robert A. Welch Foundation Grant No. C-1839 (P.D.). T.A.M was supported by the US Department of Energy, Office of Basic Energy Sciences, Materials Sciences and Engineering Division. This research used resources at the High Flux Isotope Reactor and Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory.