Observation of folded Fermi surface in the pseudogap state of high-Tc superconductor

我们用角分辨光电子能谱研究了高温超导体的赝能隙态，得到了如下实验结果。(1)我们观察到超导带和赝带两种不同的能隙共存。(2)多层铜氧化物的能隙结构已被澄清，我们已经找到了一个参数的比例与Tc。(3)虽然Tc增加退火中的电子掺杂的铜氧化物，消失的赝能隙已被观察到。这表明超导电性和赝能隙之间存在竞争。

We have investigated the pseudogap state of high-Tc superconductors by angle-resolved photoemission spectroscopy and have obtained experimental results as below. (1) We have observed a coexistence of two distinct energy gaps corresponding to the superconducting and pseudogap. (2) The energy gap structure of the multilayer cuprate has been clarified and we have found a parameter which scales with Tc. (3) While the Tc increases by annealing in the electron-doped cuprates, a disappearance of the psedogap has been observed. This indicates a competition between the superconductivity and the pseudogap.