Observation of Coulomb Gap and Enhanced Superconducting Gap in Nano-Sized Pb Islands Grown on SrTiO3  

作　　者：Yonghao Yuan Xintong Wang Canli Song Lili Wang Ke He Xucun Ma Hong Yao Wei Li Qi-Kun Xue 袁永浩;王心童;宋灿立;王立莉;何珂;马旭村;姚宏;李渭;薛其坤(State Key Laboratory of Low-Dimensional Quantum Physics,Department of Physics,Tsinghua University,Beijing 100084;Frontier Science Center for Quantum Information,Beijing 100084;Institute for Advanced Study,Tsinghua University,Beijing 100084;Beijing Academy of Quantum Information Sciences,Beijing 100193)

机构地区：[1]State Key Laboratory of Low-Dimensional Quantum Physics,Department of Physics,Tsinghua University,Beijing 100084 [2]Frontier Science Center for Quantum Information,Beijing 100084 [3]Institute for Advanced Study,Tsinghua University,Beijing 100084 [4]Beijing Academy of Quantum Information Sciences,Beijing 100193

出　　处：《Chinese Physics Letters》2020年第1期78-82,共5页中国物理快报（英文版）

基　　金：the National Natural Science Foundation under Grant Nos.11674191 and 11825404;the National Key Program for S&T Research and Development under Grant No No.2016YFA0301002;the Beijing Advanced Innovation Center for Future Chip(ICFC).W.L.was also supported by Beijing Young Talents Plan.

摘　　要：We report high-resolution scanning tunneling microscopy(STM)study of nano-sized Pb islands grown on SrTiO3,where three distinct types of gaps with different energy scales are revealed.At low temperature,we find that the superconducting gap(△s)in nano-sized Pb islands is significantly enhanced from the one in bulk Pb,while there is no essential change in superconducting transition temperature Tc,giving rise to a larger BCS ratio 2△s/kBTc^8.31 and implying stronger electron-phonon coupling.The stronger coupling can originate from the interface electron-phonon interactions between Pb islands and SrTiO3.As the superconducting gap is totally suppressed under applied magnetic field,the Coulomb gap with apparent V-shape emerges.Moreover,the size of Coulomb gap(Ac)depends on the lateral size of Pb islands(R)with △c-1/R^035,indicating that quantum size effect can significantly influence electronic correlations.Our experimental results shall shed important light on the interplay among superconductivity,quantum size effect and correlations in nano-sized strong-coupling superconductors.

关 键 词：sized stronger PHONON 

分 类 号：O469[理学—凝聚态物理]