On the superconducting symmetry of Fe-based systems - Impurity effect studies and neutron scattering measurements-

Masatoshi Sato, Yoshiaki Kobayashi, Takayuki Kawamata, Yukio Yasui, Kazunori Suzuki, M. Itoh, Ryoichi Kajimoto, Kazuhiko Ikeuchi, M. Arai, Phillipe Bourges

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

To identify the superconducting symmetry of Fe-based superconductors, we studied effects of nonmagnetic-impurities on T c, magnetic excitation spectra x″ and NMR 1/T 1 - T curve, which are sensitive to the relative signs between the order parameters on the disconnected Fermi surfaces in reciprocal space, because the symmetry is closely connected with the pairing mechanism: If the signs are opposite (symmetry S ±), the mechanism is considered to be a magnetic one, but when the signs are the same (symmetry S ++), a novel mechanism is plausible because the ordinary phonon mechanism cannot realize the T c value as high as ∼55 K found in Ln1111 (Ln=lanthanide). Results are as follows: (a) The very small rates of T c-suppression by impurity atoms M of LnFe1-yMyAs0.89-xF0.11+x (M=Ni, Co, Ru) can be explained only by S ++. (b) The x″-data for Ba(Fe, Co)2As2 (T c ∼ 23 K) and Ca-Fe-Pt-As crystals seem to be well explained by S ++ rather than by S ±. (c) The nuclear magnetic resonance data can be consistently understood by S ++, too. These results suggest the S ++ symmetry and a novel pairing mechanism, which can be considered to be related to the elastic softening of C66 induced by the orbital fluctuation of the system.

Original languageEnglish
Pages (from-to)1726-1733
Number of pages8
JournalJournal of the Korean Physical Society
Volume62
Issue number12
DOIs
Publication statusPublished - 2013 Jul 1

Keywords

  • Fe pnictide superconductors
  • Impurity effects
  • Magnetic excitation spectra
  • NMR
  • Superconducting symmetry

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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