论文标题
NMR的移位和放松以及超导杯子的电子自旋
NMR shift and relaxation and the electronic spin of superconducting cuprates
论文作者
论文摘要
最近，在核磁共振（NMR）的移位和松弛方面，建立了超导酸奶的共同现象学取得了重大进展。与旧的解释不同，结果表明，偏移需要两个具有不同温度依赖性的耦合自旋组件。一对旋转成分伴侣在平面Cu核上各向同性，并且很可能位于Planar O中，而另一个各向异性成分在平面铜$ 3D（X^2-Y^2）$轨道中具有起源。另一方面，发现核松弛对于平面铜而言是普遍存在的液体，即它独立于掺杂和材料，除了在超导过渡温度下突然下降，$ t _ {\ rm c} $。但是，有一个掺杂和材料依赖性各向异性在温度上独立于$ t _ {\ rm c} $。在这里，我们对适合所有平面Cu换档数据的变化进行了略有不同的分析。此外，我们能够得出一个简单的模型，该模型解释了基于这两个旋转成分的核松弛。特别是，迄今为止唯一的离群值也可以理解。尽管这主要涉及平面铜，但据认为，两个组件模型应适合所有丘比特的移位和放松数据。
Very recently, there has been significant progress with establishing a common phenomenology of the superconducting cuprates in terms of nuclear magnetic resonance (NMR) shift and relaxation. Different from the old interpretation, it was shown that the shifts demand two coupled spin components with different temperature dependencies. One spin component couples isotropically to the planar Cu nucleus and is likely to reside at planar O, while the other, anisotropic component has its origin in the planar copper $3d(x^2-y^2)$ orbital. Nuclear relaxation, on the other hand, was found to be rather ubiquitous and Fermi liquid-like for planar Cu, i.e., it is independent of doping and material, apart from the sudden drop at the superconducting transition temperature, $T_{\rm c}$. However, there is a doping and material dependent anisotropy that is independent on temperature, above and below $T_{\rm c}$. Here we present a slightly different analysis of the shifts that fits all planar Cu shift data. In addition we are able to derive a simple model that explains nuclear relaxation based on these two spin components. In particular, the only outlier so far, \lsco, can be understood, as well. While this concerns predominantly planar Cu, it is argued that the two component model should fit all cuprate shift and relaxation data.
