Interface-enhanced electron-phonon coupling and high-temperature superconductivity in potassium-coated ultrathin FeSe films on SrTiO3
Interface-enhanced electron-phonon coupling and high-temperature superconductivity in potassium-coated ultrathin FeSe films on SrTiO3
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SrTiO3 上钾包覆超薄 FeSe 薄膜的界面增强电子声子耦合和高温超导性
DOI：
10.1103/physrevb.93.020507
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发表时间：
2016
影响因子：
3.7
通讯作者：
Xue Qi-Kun
中科院分区：
文献类型：
--
作者：
Tang Chenjia;Liu Chong;Zhou Guanyu;Li Fangsen;Ding Hao;Li Zhi;Zhang Ding;Li Zheng;Song Canli;Ji Shuaihua;He Ke;Wang Lili;Ma Xucun;Xue Qi-Kun
用低温扫描隧道显微镜研究了碱金属（钾）在分子束外延SrTiO 3上生长的FeSe薄膜（厚度从2-UC到4-UC）上的吸附。在适当的钾覆盖率（0.2-0.3单层）下，薄膜的隧穿谱都呈现出大于11 meV的类超导带隙（是体FeSe带隙的5倍差距），并在11 meV和21 meV处呈现出两个明显的特征声子模。结果揭示了界面增强的电子-声子耦合对系统高温超导性的关键作用，并与最近的理论相一致。我们的研究提供了令人信服的证据，这种类型的异质结构超导系统的传统配对机制。
Alkali-metal (potassium) adsorption on FeSe thin films with thickness from two unit cells (UC) to 4-UC on SrTiO3 grown by molecular beam epitaxy is investigated with a low-temperature scanning tunneling microscope. At appropriate potassium coverage (0.2-0.3 monolayer), the tunneling spectra of the films all exhibit a superconducting-like gap larger than 11 meV (five times the gap value of bulk FeSe), and two distinct features of characteristic phonon modes at 11 meV and 21 meV. The results reveal the critical role of the interface enhanced electron-phonon coupling for possible high temperature superconductivity in the system and is consistent with recent theories. Our study provides compelling evidence for the conventional pairing mechanism for this type of heterostructure superconducting systems.