A Mott insulator continuously connected to iron pnictide superconductors

نویسندگان

  • Yu Song
  • Zahra Yamani
  • Chongde Cao
  • Yu Li
  • Chenglin Zhang
  • Justin S Chen
  • Qingzhen Huang
  • Hui Wu
  • Jing Tao
  • Yimei Zhu
  • Wei Tian
  • Songxue Chi
  • Huibo Cao
  • Yao-Bo Huang
  • Marcus Dantz
  • Thorsten Schmitt
  • Rong Yu
  • Andriy H Nevidomskyy
  • Emilia Morosan
  • Qimiao Si
  • Pengcheng Dai
چکیده

Iron-based superconductivity develops near an antiferromagnetic order and out of a bad-metal normal state, which has been interpreted as originating from a proximate Mott transition. Whether an actual Mott insulator can be realized in the phase diagram of the iron pnictides remains an open question. Here we use transport, transmission electron microscopy, X-ray absorption spectroscopy, resonant inelastic X-ray scattering and neutron scattering to demonstrate that NaFe1-xCuxAs near x≈0.5 exhibits real space Fe and Cu ordering, and are antiferromagnetic insulators with the insulating behaviour persisting above the Néel temperature, indicative of a Mott insulator. On decreasing x from 0.5, the antiferromagnetic-ordered moment continuously decreases, yielding to superconductivity ∼x=0.05. Our discovery of a Mott-insulating state in NaFe1-xCuxAs thus makes it the only known Fe-based material, in which superconductivity can be smoothly connected to the Mott-insulating state, highlighting the important role of electron correlations in the high-Tc superconductivity.

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عنوان ژورنال:

دوره 7  شماره 

صفحات  -

تاریخ انتشار 2016