Experimental Demonstration of a Two-Band Superconducting State for Lead Using Scanning Tunneling Spectroscopy
Experimental Demonstration of a Two-Band Superconducting State for Lead Using Scanning Tunneling Spectroscopy
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DOI：
10.1103/physrevlett.114.157001
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发表时间：
2015-04-14
影响因子：
8.6
通讯作者：
Franke, Katharina J.
中科院分区：
文献类型：
--
作者：
Ruby, Michael;Heinrich, Benjamin W.;Franke, Katharina J.
I型超导体铅（Pb）在理论上被预测为双带超导体。我们使用扫描隧道光谱（STS）解决两个超导带隙的能量差为150 μ eV。对Pb（111）、Pb（110）和Pb（100）晶体的隧穿显示出两个相干峰强度对晶体取向的强烈依赖性。我们表明，这是一个选择性隧穿到两个带的两个相干峰的能量的结果。这一点通过在亚表面缺陷周围的微分电导图中观察费米片的签名得到进一步证实。表面吸附原子对这两个能带的态密度的修正证实了这两个子带的不同轨道性质。
The type I superconductor lead (Pb) has been theoretically predicted to be a two-band superconductor. We use scanning tunneling spectroscopy (STS) to resolve two superconducting gaps with an energy difference of 150 mu eV. Tunneling into Pb(111), Pb(110), and Pb(100) crystals reveals a strong dependence of the two coherence peak intensities on the crystal orientation. We show that this is the result of a selective tunneling into the two bands at the energy of the two coherence peaks. This is further sustained by the observation of signatures of the Fermi sheets in differential conductance maps around subsurface defects. A modification of the density of states of the two bands by adatoms on the surface confirms the different orbital character of each of the two subbands.