Origin of Pressure-induced Superconducting Phase in K x Fe 2â 'y Se 2 studied by Synchrotron X-ray Diffraction and Spectroscopy

Yoshiya Yamamoto, Hitoshi Yamaoka, Masashi Tanaka, Hiroyuki Okazaki, Toshinori Ozaki, Yoshihiko Takano, Jung Fu Lin, Hidenori Fujita, Tomoko Kagayama, Katsuya Shimizu, Nozomu Hiraoka, Hirofumi Ishii, Yen Fa Liao, Ku Ding Tsuei, Jun'Ichiro Mizuki

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    15 Citations (Scopus)

    Abstract

    Pressure dependence of the electronic and crystal structures of K x Fe 2â 'y Se 2, which has pressure-induced two superconducting domes of SC I and SC II, was investigated by X-ray emission spectroscopy and diffraction. X-ray diffraction data show that compressibility along the c-axis changes around 12 GPa, where a new superconducting phase of SC II appears. This suggests a possible tetragonal to collapsed tetragonal phase transition. X-ray emission spectroscopy data also shows the change in the electronic structure around 12 GPa. These results can be explained by the scenario that the two SC domes under pressure originate from the change of Fermi surface topology. Our results here show the pronounced increase of the density of states near the Fermi surface under pressure with a structural phase transition, which can help address our fundamental understanding for the appearance of the SC II phase.

    Original languageEnglish
    Article number30946
    JournalScientific reports
    Volume6
    DOIs
    Publication statusPublished - 2016 Aug 8

    ASJC Scopus subject areas

    • General

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