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- Title
Significantly enhanced superconductivity in monolayer FeSe films on SrTiO3(001) via metallic δ-doping.
- Authors
Jiao, Xiaotong; Dong, Wenfeng; Shi, Mingxia; Wang, Heng; Ding, Cui; Wei, Zhongxu; Gong, Guanming; Li, Yanan; Li, Yuanzhao; Zuo, Binjie; Wang, Jian; Zhang, Ding; Pan, Minghu; Wang, Lili; Xue, Qi-Kun
- Abstract
Superconductivity transition temperature (T c) marks the inception of a macroscopic quantum phase-coherent paired state in fermionic systems. For 2D superconductivity, the paired electrons condense into a coherent superfluid state at T c, which is usually lower than the pairing temperature, between which intrinsic physics including Berezinskii–Kosterlitz–Thouless transition and pseudogap state are hotly debated. In the case of monolayer FeSe superconducting films on SrTiO3(001), although the pairing temperature (T p) is revealed to be 65–83 K by using spectroscopy characterization, the measured zero-resistance temperature (|${{T}}_{{\rm c}}^0$|) is limited to 20 K. Here, we report significantly enhanced superconductivity in monolayer FeSe films by δ-doping of Eu or Al on SrTiO3(001) surface, in which |${{T}}_{{\rm c}}^0$| is enhanced by 12 K with a narrowed transition width Δ T c ∼ 8 K, compared with non-doped samples. Using scanning tunneling microscopy/spectroscopy measurements, we demonstrate lowered work function of the δ-doped SrTiO3(001) surface and enlarged superconducting gaps in the monolayer FeSe with improved morphology/electronic homogeneity. Our work provides a practical route to enhance 2D superconductivity by using interface engineering.
- Subjects
SUPERCONDUCTIVITY; SUPERCONDUCTING films; SCANNING tunneling microscopy; COHERENT states; MONOMOLECULAR films; QUANTUM phase transitions; TRANSITION temperature
- Publication
National Science Review, 2024, Vol 11, Issue 3, p1
- ISSN
2095-5138
- Publication type
Article
- DOI
10.1093/nsr/nwad213