Distinguishing S-plus-minus and S-plus-plus electron pairing symmetries by neutron spin resonances in superconducting Sodium-Iron-Cobalt-Arsenic (transitional temperature = 18 Kelvin)

Das, Tanmoy¹  Balatsky, Alexander V.¹  Zhang, Chenglin²  Li, Haifeng³  Su, Yiki⁴  Nethertom, Tucker⁴  Redding, Caleb⁴  Carr, Scott⁴  Schneidewind, Astrid⁵  Faulhaber, Enrico⁶  Li, Shiliang⁷  Yao, Daoxin⁸  Bruckel, Thomas³  Dai, Pengchen⁷  Sobolev, Oleg⁵ 

[1] Los Alamos National Laboratory;University of Tennessee, Knoxville, Tennessee;Institut fur Festkorperforschung, Julich, Germany;The University of Tennessee, Knoxville, Tennessee;Forschungsneutronenquelle Heinz, Garching, Germany;Gemeinsame Forschergruppe HZB, Berlin, Germany;Institute of Physics, Chinese Academy of Sciences, Beijing, China;Sun Yat-Sen University, Guangzhou, China

关键词: ELECTRONS;    IRON;    NEUTRONS;    PNICTIDES;    RESONANCE;    SCATTERING;    SPECTRA;    SPIN;    SUPERCONDUCTIVITY;    SUPERCONDUCTORS;    SYMMETRY;   

DOI  :  10.2172/1043014
RP-ID  :  LA-UR-12-21918
PID  :  OSTI ID: 1043014
Others  :  TRN: US1203076

美国|英语

来源: SciTech Connect

【 摘 要 】

A determination of the superconducting (SC) electron pairing symmetry forms the basis for establishing a microscopic mechansim for superconductivity. For iron pnictide superconductors, the s{sup {+-}}-pairing symmetry theory predicts the presence of a sharp neutron spin resonance at an energy below the sum of hole and electron SC gap energies (E {le} 2{Delta}). Although the resonances have been observed for various iron pnictide superconductors, they are broad in energy and can also be interpreted as arising from the s{sup ++}-pairing symmetry with E {ge} 2{Delta}. Here we use inelastic neutron scattering to reveal a sharp resonance at E = 7 meV in the SC NaFe{sub 0.935}Co{sub 0.045}As (T{sub c} = 18 K). By comparing our experiments with calculated spin-excitations spectra within the s{sup {+-}} and s{sup ++}-pairing symmetries, we conclude that the resonance in NaFe{sub 0.935}Co{sub 0.045}As is consistent with the s{sup {+-}}-pairing symmetry, thus eliminating s{sup ++}-pairing symmetry as a candidate for superconductivity.