Enhancement of the critical temperature of the pnictide superconductor LaFeAsO1-xFx studied via75As NMR under pressure

Tatsuya Nakano, Naoki Fujiwara, Kenichiro Tatsumi, Hironari Okada, Hiroki Takahashi, Yoichi Kamihara, Masahiro Hirano, Hideo Hosono

Research output: Contribution to journalArticle

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Abstract

Nuclear-magnetic-resonance measurements of an iron (Fe)-based superconductor LaFeAsO1-xFx (x=0.08 and 0.14) were performed at ambient pressure and under pressure. The relaxation rate 1/ T 1 for the overdoped samples (x=0.14) shows T -linear behavior just above Tc, and pressure application enhances 1/T1 T similar to the behavior of Tc This implies that 1/T1 T=constant originates from the Korringa relation, and an increase in the density of states at the Fermi energy D (EF) leads to the enhancement of Tc. In the underdoped samples (x=0.08), 1/ T1 measured at ambient pressure also shows T -linear behavior in a wide temperature range above Tc. However, 1/ T1 T shows Curie-Weiss-type T dependence at 3.0 GPa accompanied by a small increase in Tc, suggesting that predominant low-frequency antiferromagnetic fluctuation is not important for development of superconductivity or remarkable enhancement of Tc. The qualitatively different features between underdoped and overdoped samples are systematically explained by a band calculation with hole and electron pockets.

Original languageEnglish
Article number100510
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume81
Issue number10
DOIs
Publication statusPublished - 2010 Mar 22
Externally publishedYes

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Group 5A compounds
Superconducting materials
critical temperature
Nuclear magnetic resonance
nuclear magnetic resonance
augmentation
Magnetic resonance measurement
Temperature
Superconductivity
Fermi level
superconductivity
Iron
low frequencies
iron
Electrons
electrons
temperature
energy

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

Enhancement of the critical temperature of the pnictide superconductor LaFeAsO1-xFx studied via75As NMR under pressure. / Nakano, Tatsuya; Fujiwara, Naoki; Tatsumi, Kenichiro; Okada, Hironari; Takahashi, Hiroki; Kamihara, Yoichi; Hirano, Masahiro; Hosono, Hideo.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 81, No. 10, 100510, 22.03.2010.

Research output: Contribution to journalArticle

Nakano, Tatsuya ; Fujiwara, Naoki ; Tatsumi, Kenichiro ; Okada, Hironari ; Takahashi, Hiroki ; Kamihara, Yoichi ; Hirano, Masahiro ; Hosono, Hideo. / Enhancement of the critical temperature of the pnictide superconductor LaFeAsO1-xFx studied via75As NMR under pressure. In: Physical Review B - Condensed Matter and Materials Physics. 2010 ; Vol. 81, No. 10.
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