Unconventional Multi-gap Superconductivity and Antiferromagnetic Spin Fluctuations in New Iron-arsenide LaFe2As2 in Heavily Electron-doped Regime
Unconventional Multi-gap Superconductivity and Antiferromagnetic Spin Fluctuations in New Iron-arsenide LaFe2As2 in Heavily Electron-doped Regime
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DOI：
10.7566/jpsj.88.113702
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发表时间：
2019-09
影响因子：
1.7
通讯作者：
T. Kouchi;M. Yashima;H. Mukuda;S. Ishida;H. Eisaki;Y. Yoshida;Kenji Kawashima;A. Iyo
中科院分区：
文献类型：
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作者：
T. Kouchi;M. Yashima;H. Mukuda;S. Ishida;H. Eisaki;Y. Yoshida;Kenji Kawashima;A. Iyo
本文报道了新的铁砷化合物（La_（0.5-x）Na_（0.5 +x））Fe_2As_2的~（75）As-NMR/NQR结果。x=0的母体化合物在T_N=130 K以下表现出条带型反铁磁（AFM）有序。在空穴掺杂x=+0.3和重电子掺杂x=-0.5处测量的核自旋弛豫速率表明，正常态性质受原子力显微镜自旋涨落（AFMSFs）的支配，在x=+0.3处比x=-0.5处更显著.它们的超导相具有非常规的多能隙超导态，其中较小的超导能隙共同变得特别弱。实验结果表明，从空穴掺杂态到重电子掺杂态，AFMSFs与SC之间存在着密切的关系，揭示了在重电子掺杂状态下出现的一种独特的SC相，它在形式上等价于非SC化合物Ba（Fe0.5Co0.5）Fe 2As 2.
We report 75As-NMR/NQR results on new iron-arsenide compounds (La0.5-xNa0.5+x)Fe2As2. The parent compound x=0 exhibits a stripe-type antiferromagnetic (AFM) order below T_N=130 K. The measurement of nuclear spin relaxation rate at hole-doped x=+0.3 and heavily electron-doped x=-0.5 revealed that the normal-state properties are dominated by AFM spin fluctuations (AFMSFs), which are more significant at x=+0.3 than at x=-0.5. Their superconducting (SC) phases are characterized by unconventional multi-gap SC state, where the smaller SC gaps are particularly weaken in common. The experimental results indicate the close relationship between the AFMSFs and the SC from the hole-doped state to heavily electron-doped state, which shed light on a unique SC phase emerged in the heavily electron-doped regime being formally equivalent to non-SC compound Ba(Fe0.5Co0.5)Fe2As2.