Evidence of cooperative effect on the enhanced superconducting transition temperature at the FeSe/SrTiO<sub>3</sub> interface.

Song, Q; Yu, T L; Lou, X; Xie, B P; Xu, H C; Wen, C H P; Yao, Q; Zhang, S Y et al. · Nat Commun · 2019

basic_science · Level V

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Abstract

At the interface between monolayer FeSe films and SrTiO<sub>3</sub> substrates the superconducting transition temperature (T<sub>c</sub>) is unexpectedly high, triggering a surge of excitement. The mechanism for the T<sub>c</sub> enhancement has been the central question, as it may present a new strategy for seeking out higher T<sub>c</sub> materials. To reveal this enigmatic mechanism, by combining advances in high quality interface growth, <sup>16</sup>O [Formula: see text] <sup>18</sup>O isotope substitution, and extensive data from angle resolved photoemission spectroscopy, we provide striking evidence that the high T<sub>c</sub> in FeSe/SrTiO<sub>3</sub> is the cooperative effect of the intrinsic pairing mechanism in the FeSe and interactions between the FeSe electrons and SrTiO<sub>3</sub> phonons. Furthermore, our results point to the promising prospect that similar cooperation between different Cooper pairing channels may be a general framework to understand and design high-temperature superconductors.