Superconductivity in Correlated Multi-Orbital Systems with Spin-Orbit Coupling: Coexistence of Even- and Odd-Frequency Pairing and the Case of Strontium Ruthenate
Olivier Gingras, Nikita Allaglo, Reza Nourafkan, Michel Côté, André-Marie S. Tremblay
The superconducting order parameter of strontium ruthenate is the center of a lasting puzzle calling for theoretical studies that include the seldom-considered effects of spin-orbit coupling and the frequency-dependence of the order parameters. Here we generalize the frequency-dependent theory of superconductivity mediated by spin and charge fluctuations to include spin-orbit coupling in multi-orbital systems and we characterize the superconducting states using the spin-parity-orbital-time $SPOT$ quantum numbers, group theory, and phase distributions in the complex plane. We derive a pseudospin formulation that maps the inter-pseudospin sector of the normal state Eliashberg equation to a pseudospin-diagonal one. Possible superconducting order parameters for strontium ruthenate are obtained starting from a realistic density-functional-theory normal state. We find that spin-orbit coupling leads to ubiquitous entanglement of spin and orbital quantum numbers, along with notable mixing between even- and odd-frequency correlations. We propose a phase diagram obtained from the temperature dependence of the leading and subleading symmetries in the pseudospin-orbital basis. An accidental degeneracy between leading inter-pseudospin symmetries in strontium ruthenate, B$_{1g}^+$ and A$_{2g}^-$, could resolve apparent experimental contradictions.
Proposal to stabilize and detect half-quantum vortices in strontium ruthenate thin films: Non-Abelian braiding statistics of vortex matter in a ${p_x}+i{p_y}$ superconductor
Dynamic nanoscale structural correlations in strontium ruthenate
University of Zagreb（萨格勒布大学）；University of Minnesota（明尼苏达大学）；Indian Institute of Technology Jammu（詹穆印度理工学院）；Oak Ridge National Laboratory（橡树岭国家实验室）；Max-Planck-Institute for the Chemical Physics of Solids（马克斯·普朗克固体化学物理研究所）；Argonne National Laboratory（阿贡国家实验室）
Coexistence of ferromagnetism and superconductivity in the hybrid ruthenate-cuprate compound RuSr_2GdCu_2O_8 studied by muon spin rotation (μSR) and DC-magnetization
Fractional power-law behavior and its origin in iron-chalcogenide and ruthenate superconductors: Insights from first-principles calculations
我们进行现实的第一性原理计算的铁硫族化合物和铁基材料，以确定在这些系统中的洪德耦合诱导的相关性的实验签名。我们发现FeTe和KPDMATHABMM Fe $_{2-y}$ Se $_2$在它们的准粒子自能和光学电导率中显示出不寻常的轨道依赖分数幂律行为，这一现象首先在SrRuO $_3$中发现。这些材料的顺磁状态中的强不相干性导致电子状态隐藏在角度分辨光电子能谱中，其在低温下重新出现。我们确定了有效的低能量哈密顿描述这些系统，并表明这些异常是不控制的接近量子临界点，但从共存的快速量子力学轨道波动和慢自旋波动的结果。
Sixfold enhancement of superconductivity in a tunable electronic nematic system
其中电子自由度降低晶体旋转对称性的电子超导相是许多高温超导体中的常见图案。然而，理解向列性和磁涨落在库珀配对中的作用和影响往往因其他有序的共存而变得复杂，特别是长程磁有序。在这里，我们报告的增强的超导电性在一个模型的电子超导系统的磁性缺失，并表明，增强直接出生的强烈的超导波动所发出的调谐量子相变。我们使用的Ba $_{1-x}$ Sr $_{x}$ Ni $_2$作为$_2$取代系列的弹性电阻测量表明，锶取代促进电子驱动的$B_{1g}$在这个系统中的顺序，并且该顺序的完全抑制到绝对零度温度引起了显着增强的配对强度，证明了六倍增加的超导转变温度。在这个模型系统中，增强配对和电子涨落之间的直接关系，以及与单向电荷密度波序的相互作用，可与铜酸盐中发现的相媲美，提供了一种手段来阐明向列性在提高超导性中的作用。
