Electron pockets in the Fermi surface of hole-doped high-Tc superconductors
Electron pockets in the Fermi surface of hole-doped high-Tc superconductors
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DOI：
10.1038/nature06332
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发表时间：
2007-11-22
期刊：
影响因子：
64.8
通讯作者：
Taillefer, Louis
中科院分区：
文献类型：
--
作者：
LeBoeuf, David;Doiron-Leyraud, Nicolas;Taillefer, Louis
铜氧化物中的高温超导性发生在当材料被化学调谐以具有在高掺杂的金属状态和零掺杂的绝缘状态之间的载流子浓度时。在没有超导性的情况下，电子系统的基本演化仍然不清楚，一个重要的问题是它是否涉及任何对称性破缺的中间相（1）。在欠掺杂的“YBCO”材料YBa 2Cu 3 Oy和YBa 2Cu 4 O 8中的电子态的费米表面最近被示出包括小口袋（2-4），与表征过掺杂区域（5）的大圆柱体形成对比，指出费米表面中的拓扑变化。在这里，我们报告了一个负的霍尔电阻的观察在磁场诱导的正常状态的YBa 2Cu 3 Oy和YBa 2Cu 4 O 8，这表明这些口袋是电子类，而不是空穴类。我们认为，这些电子袋最有可能是由密度波相的出现引起的费米面重构引起的，正如人们认为在反铁磁序开始附近的电子掺杂氧化铜中发生的那样（6，7）。与表现出自旋/电荷密度波序（8-11）的La 2CuO 4系列材料的比较表明，费米表面重构也发生在这些材料中，指向高转变温度（T-c）超导体的一般性质。
High-temperature superconductivity in copper oxides occurs when the materials are chemically tuned to have a carrier concentration intermediate between their metallic state at high doping and their insulating state at zero doping. The underlying evolution of the electron system in the absence of superconductivity is still unclear, and a question of central importance is whether it involves any intermediate phase with broken symmetry(1). The Fermi surface of the electronic states in the underdoped 'YBCO' materials YBa2Cu3Oy and YBa2Cu4O8 was recently shown to include small pockets(2-4), in contrast with the large cylinder that characterizes the overdoped regime(5), pointing to a topological change in the Fermi surface. Here we report the observation of a negative Hall resistance in the magnetic-field-induced normal state of YBa2Cu3Oy and YBa2Cu4O8, which reveals that these pockets are electron-like rather than hole-like. We propose that these electron pockets most probably arise from a reconstruction of the Fermi surface caused by the onset of a density-wave phase, as is thought to occur in the electron-doped copper oxides near the onset of antiferromagnetic order(6,7). Comparison with materials of the La2CuO4 family that exhibit spin/charge density-wave order(8-11) suggests that a Fermi surface reconstruction also occurs in those materials, pointing to a generic property of high-transition-temperature (T-c) superconductors.