Microscopic charging and in-gap states in superconducting granular aluminum
Microscopic charging and in-gap states in superconducting granular aluminum
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DOI：
10.1103/physrevb.102.104502
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发表时间：
2019-11
影响因子：
3.7
通讯作者：
Fang Yang;Thomas Gozlinski;Tim Storbeck;L. Grünhaupt;I. Pop;W. Wulfhekel
中科院分区：
文献类型：
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作者：
Fang Yang;Thomas Gozlinski;Tim Storbeck;L. Grünhaupt;I. Pop;W. Wulfhekel
我们提出了超导颗粒铝薄膜局部电子结构的扫描隧道显微镜（STM）测量。 STM 光谱显示，与铝相比，超导能隙在莫特电阻率 ${\ensuremath{\rho}}_{\mathrm{M}}\ensuremath{\approx}400\ensuremath{\mu}\mathrm{\ensuremath{\Omega}}\phantom{\rule{0.16em}{0ex}}\mathrm{cm}$ 附近和之上均匀增加。在${\ensuremath{\rho}}_{\mathrm{M}}$上方，我们发现了库仑充电效应，这是电去耦的第一个迹象，以及单个颗粒上的带隙状态，这可能会导致量子器件中的通量噪声和介电损耗。我们还观察到带隙外的多个低能态，这表明玻色子激发的能量低于超导带隙的两倍。
We present scanning tunneling microscope (STM) measurements of the local electronic structure of superconducting granular aluminium films. The STM spectra show a homogeneously increased superconducting gap compared to that of aluminum, both near and above the Mott resistivity ${\ensuremath{\rho}}_{\mathrm{M}}\ensuremath{\approx}400\ensuremath{\mu}\mathrm{\ensuremath{\Omega}}\phantom{\rule{0.16em}{0ex}}\mathrm{cm}$. Above ${\ensuremath{\rho}}_{\mathrm{M}}$ we find Coulomb charging effects, a first indication of electrical decoupling, and in-gap states on individual grains, which could contribute to flux noise and dielectric loss in quantum devices. We also observe multiple low-energy states outside the gap, which indicate bosonic excitations of an energy below twice the superconducting gap.