Bruér Jens, Maggio-Aprile Ivan, Jenkins Nathan, Ristić Zoran, Erb Andreas, Berthod Christophe, Fischer Øystein, Renner Christoph
Department of Quantum Matter Physics, University of Geneva, 24 quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner-Strasse 8, D-85748 Garching, Germany.
Nat Commun. 2016 Mar 31;7:11139. doi: 10.1038/ncomms11139.
The observation by scanning tunnelling spectroscopy of Abrikosov vortex cores in the high-temperature superconductor YBa2Cu3O7-δ (Y123) has revealed a robust pair of electron-hole symmetric states at finite subgap energy. Their interpretation remains an open question because theory predicts a different signature in the vortex cores, characterized by a strong zero-bias conductance peak. Here, we present scanning tunnelling spectroscopy data on very homogeneous Y123 at 0.4 K revealing that the subgap features do not belong to vortices: they are actually observed everywhere along the surface with high spatial and energy reproducibility, even in the absence of magnetic field. Detailed analysis and modelling show that these states remain unpaired in the superconducting phase and belong to an incoherent channel, which contributes to the tunnelling signal in parallel with the superconducting density of states.
通过扫描隧道谱对高温超导体YBa2Cu3O7-δ（Y123）中的阿布里科索夫涡旋核进行观测，发现了在有限能隙能量处存在一对稳健的电子-空穴对称态。它们的解释仍然是一个悬而未决的问题，因为理论预测涡旋核中有不同的特征，其特点是有一个很强的零偏置电导峰。在此，我们展示了在0.4 K下对非常均匀的Y123进行扫描隧道谱的数据，表明能隙以下的特征并不属于涡旋：实际上在整个表面都能观察到它们，具有很高的空间和能量重复性，即使在没有磁场的情况下也是如此。详细的分析和建模表明，这些态在超导相中保持未配对状态，属于一个非相干通道，它与超导态密度并行地对隧道信号做出贡献。
