Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
Phys Rev Lett. 2010 Jun 4;104(22):227001. doi: 10.1103/PhysRevLett.104.227001. Epub 2010 Jun 1.
We report the first observation of the multilayer band splitting in the optimally doped trilayer cuprate Bi2Sr2Ca2Cu3O(10+δ) (Bi2223) by angle-resolved photoemission spectroscopy. The observed energy bands and Fermi surfaces are originated from the outer and inner CuO2 planes (OP and IP). The OP band is overdoped with a large d-wave gap around the node of Δ0∼43 meV while the IP is underdoped with an even large gap of Δ0∼60 meV. These energy gaps are much larger than those for the same doping level of the double-layer cuprates, which leads to the large Tc in Bi2223. We propose possible origins of the large superconducting gaps for the OP and IP: (1) minimal influence of out-of-plane disorder and a proximity effect and (2) interlayer tunneling of Cooper pairs between the OP and IP.
我们通过角分辨光电子能谱首次观察到了最优掺杂的三层铜酸盐 Bi2Sr2Ca2Cu3O(10+δ)（Bi2223）中的多层能带分裂。观察到的能带和费米面来源于外和内 CuO2 平面（OP 和 IP）。OP 带在节点附近的 d 波隙较大，约为Δ0∼43 毫电子伏特，而 IP 带则过度掺杂，隙更大，约为Δ0∼60 毫电子伏特。这些能隙比双层铜酸盐在相同掺杂水平下的能隙大得多，这导致了 Bi2223 中的大 Tc。我们提出了 OP 和 IP 中超导能隙较大的可能起源：（1）平面外无序和近邻效应的最小影响，（2）OP 和 IP 之间的 Cooper 对层间隧道。
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