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arXiv 1701.02773cond-mat.str-el
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Sr $_2$ RuO $_4$准一维能带中的准粒子干涉和强电子模耦合

Quasiparticle Interference and Strong Electron-Mode Coupling in the Quasi-One-Dimensional Bands of Sr$_2$RuO$_4$

Zhenyu Wang, Daniel Walkup, Philip Derry, Thomas Scaffidi, Melinda Rak, Sean Vig, Anshul Kogar, Ilija Zeljkovic, Ali Husain, Luiz H. Santos, Yuxuan Wang, Andrea… 展开作者

Zhenyu Wang, Daniel Walkup, Philip Derry, Thomas Scaffidi, Melinda Rak, Sean Vig, Anshul Kogar, Ilija Zeljkovic, Ali Husain, Luiz H. Santos, Yuxuan Wang, Andrea Damascelli, Yoshiteru Maeno, Peter Abbamonte, Eduardo Fradkin, Vidya Madhavan

摘要:

单层的单齿Sr $_2$ RuO $_4$作为一种自旋三重态超导体引起了人们极大的兴趣,其序参量可能会破坏时间反演不变性,并具有Majorana零模的半量子化涡旋。虽然超导状态的实际性质仍然是一个有争议的问题,但长期以来人们一直认为它是从传统费米液体很好地描述的金属状态凝结而成的。在这项工作中,我们使用的傅里叶变换扫描隧道光谱(FT-STS)和动量分辨电子能量损失谱(M-EELS)相结合的探测在正常状态的Sr $_2$ RuO $_4$的相互作用的影响。我们的高分辨率FT-STS数据显示了具有明显准一维(1D)特征的β带特征。带色散揭示了令人惊讶的强相互作用的影响,显着重整的费米速度,这表明正常状态的Sr $_2$ RuO $_4$是一个“相关金属”的相关性得到加强的准一维性质的频带。此外,在大约10 meV,38 meV和70 meV的能量的扭结观察。通过比较STM和M-EELS数据,我们表明,这两个更高的能量的功能产生与集体模式的耦合。强关联效应和准一维带中的扭折现象为理解超导态提供了重要信息。这项工作开辟了一个独特的方法来揭示超导序参量在这种化合物。

英文摘要:

The single-layered ruthenate Sr$_2$RuO$_4$ has attracted a great deal of interest as a spin-triplet superconductor with an order parameter that may potentially break time reversal invariance and host half-quantized vortices with Majorana zero modes. While the actual nature of the superconducting state is still a matter of controversy, it has long been believed that it condenses from a metallic state that is well described by a conventional Fermi liquid. In this work we use a combination of Fourier transform scanning tunneling spectroscopy (FT-STS) and momentum resolved electron energy loss spectroscopy (M-EELS) to probe interaction effects in the normal state of Sr$_2$RuO$_4$. Our high-resolution FT-STS data show signatures of the β-band with a distinctly quasi-one-dimensional (1D) character. The band dispersion reveals surprisingly strong interaction effects that dramatically renormalize the Fermi velocity, suggesting that the normal state of Sr$_2$RuO$_4$ is that of a 'correlated metal' where correlations are strengthened by the quasi 1D nature of the bands. In addition, kinks at energies of approximately 10meV, 38meV and 70meV are observed. By comparing STM and M-EELS data we show that the two higher energy features arise from coupling with collective modes. The strong correlation effects and the kinks in the quasi 1D bands may provide important information for understanding the superconducting state. This work opens up a unique approach to revealing the superconducting order parameter in this compound.

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