Persistent superconductivity in ultrathin Pb films: A scanning tunneling spectroscopy study
Persistent superconductivity in ultrathin Pb films: A scanning tunneling spectroscopy study
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DOI：
10.1103/physrevlett.96.027005
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发表时间：
2006-01-20
影响因子：
8.6
通讯作者：
Shih, CK
中科院分区：
文献类型：
--
作者：
Eom, D;Qin, S;Shih, CK
用低温扫描隧道显微镜研究了外延生长Pb薄膜在超导区（5-18 ML）的超导能隙与层厚的关系。层相关的能隙和转变温度（Tc）显示持续的量子振荡到最低的厚度没有任何抑制的迹象。此外，通过与T-c以上量子阱态的测量和理论计算的比较，我们发现T-c振荡与E-F处的态密度振荡直接相关。该振荡表现为费米波长和层厚度的相位匹配，导致由较长波长量子拍调制的双层周期性。
By using a low temperature scanning tunneling microscope we have probed the superconducting energy gap of epitaxially grown Pb films as a function of the layer thickness in an ultrathin regime (5-18 ML). The layer-dependent energy gap and transition temperature (T-c) show persistent quantum oscillations down to the lowest thickness without any sign of suppression. Moreover, by comparison with the quantum-well states measured above T-c and the theoretical calculations, we found that the T-c oscillation correlates directly with the density of states oscillation at E-F. The oscillation is manifested by the phase matching of the Fermi wavelength and the layer thickness, resulting in a bilayer periodicity modulated by a longer wavelength quantum beat.