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Unconventional Superconductivity (USC) in layered Sr$_{2}$RuO$_{4}$ is of long-standing interest because it is long thought to be a superconducting analogue of $^{3}He$. However, resurgence of recent data points toward a much more involved pairing symmetry, where the interplay between multi-band character, sizable multi-band electronic correlations and strong spin-orbit coupling conspires to select an apparently rather unusual, hitherto unknown, USC pair symmetry. This mandates detailed revisiting of the normal state and, in particular, of the $T$-dependent incoherence-coherence crossover. Here, using a modern first-principles correlated view, we study this issue in the real structure of Sr$_{2}$RuO$_{4}$ in detail and present a unified and quantitative description of a range of unusual physical responses in the normal state across the crossover. Armed with these strengths, we propose that a new and important element, that of dominant (quasi-one-dimensional $xz,yz$) interband charge fluctuations in a ``Hund'' metal, may be a primary pair glue for USC in this system. We will emphasize internal consistency of our proposed scenario vis-a-vis a wide range of constraints imposed by extant data.

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Mukul Laad, University of Chennai
Seminar Room Kernphysik
Contact: Simon Trebst