Superconductivity and Antiferromagnetic Spin Fluctuations in LaFe(As1_xPx)(O1_yFy) probed by 31P-NMR

International Conference on Strongly Correlated Electron Systems 2016

Shiota, T.^1 ; Mukuda, H.^1 ; Uekubo, M.^2 ; Engetsu, F.^1 ; Yashima, M.^1 ; Kitaoka, Y.^1 ; Lai, K.T.^2 ; Usui, H.^2 ; Kuroki, K.^2 ; Miyasaka, S.^2 ; Tajima, S.^2

Graduate School of Engineering Science, Osaka University, Osaka

560-8531, Japan^1

Graduate School of Science, Osaka University, Osaka

560-0043, Japan^2

关键词: Antiferromagnetic spin fluctuations;    D orbitals;    Finite energy;    High temperature;    Iron pnictide superconductors;    Low temperatures;    Non-monotonic variation;    Temperature evolution;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/807/5/052006/pdf
DOI  :  10.1088/1742-6596/807/5/052006

来源: IOP

【 摘 要 】

31P-NMR study on LaFe(As1-xPx)(O0.86F0.14) unraveled that antiferromagnetic spin fluctuations (AFMSFs) emerge significantly at x=0.4 where the Tcis markedly enhanced, indicating that the AFMSFs are one of the important factors for raising Tc. From extensive comparison over wide compositions for 0 ≤ x ≤1 and 0 ≤ y ≤ 0.14, we revealed that there are two different types in temperature evolution of the AFMSFs: One is enhanced particularly at low energies that evolves only at low temperatures, which mainly derives from the two orbitals of dxz/yz. The other is distributed broadly at finite energies that appears up to high temperatures, which derives from three orbitals of dxyand dxz/yz. The highest Tc(=27 K) state in the present compositions appears at (x, y)=(0.4, 0.1) where two characteristics of AFMSFs merge, suggesting the contribution of the AFMSFs over wide energies to the onset of SC. The nonmonotonic variation of Tcin LaFe(As1-xPx)(O1-yFy) is attributed to the AFMSFs from degenarated multiple-3d-orbitals on iron-pnictide superconductors.