Relating atomic-scale electronic phenomena to wave-like quasiparticle states in superconducting Bi2Sr2CaCu2O8+δ
Relating atomic-scale electronic phenomena to wave-like quasiparticle states in superconducting Bi2Sr2CaCu2O8+δ
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DOI：
10.1038/nature01496
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发表时间：
2003-04-10
期刊：
影响因子：
64.8
通讯作者：
Davis, JC
中科院分区：
文献类型：
--
作者：
McElroy, K;Simmonds, RW;Davis, JC
简单晶体固体的电子结构可以完全用真实的空间（r-空间）中的局域量子态或定义在动量空间（k-空间）中的类波态来描述。然而，在铜氧化物超导体中，仅这些描述中的任何一个都可能是不够的。事实上，Bi 2Sr 2CaCu 2 O 8 + δ（Bi-2212）的r-空间（1-5）和k-空间（6-13）研究之间的比较揭示了许多无法解释的现象和明显的矛盾。在这里，为了探索这些问题，我们报告的Bi-2212态密度的原子尺度的空间调制的傅里叶变换研究。当分析为由准粒子干涉引起时（14-16），调制产生的费米面和能隙的元素与光电发射实验一致（12，13）。与准粒子干涉模型的色散调制的许多套的一致性表明，不需要额外的序参量。我们还探讨了动量空间结构的未被占领的国家是无法访问的光电发射，并发现强烈的相似性的结构的占领状态。因此，氧化铜准粒子显然表现出类似于传统超导体的粒子-空穴混合。在能隙最大值附近，调制变得强烈，与晶体相称，并以纳米级域为界（4）。因此，散射的波腹准粒子的强烈影响纳米尺度的无序。
The electronic structure of simple crystalline solids can be completely described in terms either of local quantum states in real space (r-space), or of wave-like states defined in momentum-space (k-space). However, in the copper oxide superconductors, neither of these descriptions alone may be sufficient. Indeed, comparisons between r-space(1-5) and k-space(6-13) studies of Bi2Sr2CaCu2O8+delta (Bi-2212) reveal numerous unexplained phenomena and apparent contradictions. Here, to explore these issues, we report Fourier transform studies of atomic-scale spatial modulations in the Bi-2212 density of states. When analysed as arising from quasiparticle interference(14-16), the modulations yield elements of the Fermi-surface and energy gap in agreement with photoemission experiments(12,13). The consistency of numerous sets of dispersing modulations with the quasiparticle interference model shows that no additional order parameter is required. We also explore the momentum-space structure of the unoccupied states that are inaccessible to photoemission, and find strong similarities to the structure of the occupied states. The copper oxide quasiparticles therefore apparently exhibit particle-hole mixing similar to that of conventional superconductors. Near the energy gap maximum, the modulations become intense, commensurate with the crystal, and bounded by nanometre-scale domains(4). Scattering of the antinodal quasiparticles is therefore strongly influenced by nanometre-scale disorder.