Asulin Itay, Sharoni Amos, Yulli Ofer, Koren Gad, Millo Oded
Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel.
Phys Rev Lett. 2004 Oct 8;93(15):157001. doi: 10.1103/PhysRevLett.93.157001. Epub 2004 Oct 4.
Scanning tunneling spectroscopy of (110)YBa(2)Cu(3)O(7-delta)/Au bilayers reveal a proximity effect markedly different from the conventional one. While proximity-induced mini-gaps rarely appear in the Au layer, the Andreev bound states clearly penetrate into the metal. Zero bias conductance peaks are measured on Au layers thinner than 7 nm with a magnitude similar to those detected on the bare superconductor films. The peaks then decay abruptly with Au thickness and disappear above 10 nm. This length is shorter than the normal coherence length and corresponds to the (ballistic) mean free path.
(110)YBa(2)Cu(3)O(7-δ)/Au双层膜的扫描隧道谱显示出与传统近邻效应明显不同的近邻效应。虽然近邻诱导的小能隙在金层中很少出现，但安德烈夫束缚态明显渗透到金属中。在厚度小于7纳米的金层上测量到零偏置电导峰，其大小与在裸超导薄膜上检测到的相似。然后，这些峰随金层厚度急剧衰减，并在10纳米以上消失。这个长度比正常相干长度短，对应于（弹道）平均自由程。
