Hanaguri T, Kohsaka Y, Ono M, Maltseva M, Coleman P, Yamada I, Azuma M, Takano M, Ohishi K, Takagi H
Magnetic Materials Laboratory, RIKEN Advanced Science Institute, Wako 351-0198, Japan.
Science. 2009 Feb 13;323(5916):923-6. doi: 10.1126/science.1166138. Epub 2009 Jan 22.
When electrons pair in a superconductor, quasi-particles develop an acute sensitivity to different types of scattering potential that is described by the appearance of coherence factors in the scattering amplitudes. Although the effects of coherence factors are well established in isotropic superconductors, they are much harder to detect in their anisotropic counterparts, such as high-superconducting-transition-temperature cuprates. We demonstrate an approach that highlights the momentum-dependent coherence factors in Ca2-xNaxCuO2Cl2. We used Fourier-transform scanning tunneling spectroscopy to reveal a magnetic-field dependence in quasi-particle scattering interference patterns that is sensitive to the sign of the anisotropic gap. This result is associated with the d-wave coherence factors and quasi-particle scattering off vortices. Our technique thus provides insights into the nature of electron pairing as well as quasi-particle scattering processes in unconventional superconductors.
当电子在超导体中配对时，准粒子会对不同类型的散射势产生敏锐的敏感性，这可通过散射振幅中相干因子的出现来描述。尽管相干因子的效应在各向同性超导体中已得到充分证实，但在诸如高超导转变温度铜酸盐等各向异性超导体中却很难检测到。我们展示了一种突出Ca2-xNaxCuO2Cl2中动量相关相干因子的方法。我们使用傅里叶变换扫描隧道谱来揭示准粒子散射干涉图案中对各向异性能隙符号敏感的磁场依赖性。这一结果与d波相干因子以及准粒子从涡旋的散射有关。因此，我们的技术为非常规超导体中电子配对的本质以及准粒子散射过程提供了深入见解。
