Meng Jianqiao, Liu Guodong, Zhang Wentao, Zhao Lin, Liu Haiyun, Jia Xiaowen, Mu Daixiang, Liu Shanyu, Dong Xiaoli, Zhang Jun, Lu Wei, Wang Guiling, Zhou Yong, Zhu Yong, Wang Xiaoyang, Xu Zuyan, Chen Chuangtian, Zhou X J
National Laboratory for Superconductivity, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Nature. 2009 Nov 19;462(7271):335-8. doi: 10.1038/nature08521.
In the pseudogap state of the high-transition-temperature (high-T(c)) copper oxide superconductors, angle-resolved photoemission (ARPES) measurements have seen Fermi arcs-that is, open-ended gapless sections in the large Fermi surface-rather than a closed loop expected of an ordinary metal. This is all the more puzzling because Fermi pockets (small closed Fermi surface features) have been suggested by recent quantum oscillation measurements. The Fermi arcs cannot be understood in terms of existing theories, although there is a solution in the form of conventional Fermi surface pockets associated with competing order, but with a back side that is for detailed reasons invisible to photoemission probes. Here we report ARPES measurements of Bi(2)Sr(2-x)La(x)CuO(6+delta) (La-Bi2201) that reveal Fermi pockets. The charge carriers in the pockets are holes, and the pockets show an unusual dependence on doping: they exist in underdoped but not overdoped samples. A surprise is that these Fermi pockets appear to coexist with the Fermi arcs. This coexistence has not been expected theoretically.
在高温转变温度（高Tc）铜氧化物超导体的赝能隙状态下，角分辨光电子能谱（ARPES）测量发现了费米弧，即在大费米面中的开放式无隙部分，而不是普通金属所预期的闭环。这更令人困惑，因为最近的量子振荡测量表明存在费米口袋（小的封闭费米面特征）。尽管存在一种以与竞争序相关的传统费米面口袋形式的解决方案，但由于详细原因，光电子能谱探针无法看到其背面，所以费米弧无法用现有理论来解释。在此，我们报告了对Bi(2)Sr(2-x)La(x)CuO(6+δ)（La-Bi2201）的ARPES测量，结果揭示了费米口袋。口袋中的载流子为空穴，并且这些口袋对掺杂表现出不寻常的依赖性：它们存在于欠掺杂而非过掺杂的样品中。令人惊讶的是，这些费米口袋似乎与费米弧共存。从理论上并未预期到这种共存情况。
