59Co and 75As NMR Investigation of Electron-Doped High Tc Superconductor BaFe1.8Co0.2As2 (Tc=22 K)

Journal Article · Wed Oct 15 04:00:00 EDT 2008 · Journal of the Physical Society of Japan

DOI:https://doi.org/10.1143/JPSJ.77.103705· OSTI ID:1014218

Ning, F. L. ^[1]; Ahilan, K. ^[1]; Imai, T. ^[1]; Safa-Sefat, Athena ^[2]; Jin, Rongying ^[2]; McGuire, Michael A ^[2]; Sales, Brian C ^[2]; Mandrus, David ^[2]

---

1. McMaster University
2. ORNL

We report an NMR investigation of the superconductivity in BaFe{sub 2}As{sub 2} induced by Co doping (T{sub c} = 22 K). We demonstrate that Co atoms form an alloy with Fe atoms and donate carriers without creating localized moments. Our finding strongly suggests that the underlying physics of iron-pnictide superconductors is quite different from the widely accepted physical picture of high T{sub c} cuprates as doped Mott insulators. We also show a crossover of electronic properties into a low temperature pseudo-gap phase with a pseudo-gap {Delta}{sub PG}/k{sub B} -560 K, where {chi}{sub spin} -constant and resisitivty {rho} {proportional_to} T. The NMR Knight shift below T{sub c} decreases for both along the c-axis and ab-plane, and is consistent with the singlet pairing scenario.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1014218
• Journal Information: Journal of the Physical Society of Japan, Journal Name: Journal of the Physical Society of Japan Journal Issue: 10 Vol. 77; ISSN 0031-9015
• Country of Publication: United States
• Language: English