IMX Talks - Interlayer coherence at room temperature in high Tc cuprates and photo-induced superconductivity

In the past decade, photo-induced superconducting-like behaviors have been reported in a number of materials driven by intense pump fields. Of particular interest is the high-Tc cuprate YBa2Cu2O{6+x}(YBCO), where such effect has been reported up to the so-called pseudogap temperature T* ~ 300-400 K. In a recent tour-de-force experiment, a transient magnetic field which is proportional to and in the same direction of an applied field has been observed outside the sample, suggestive of flux exclusion due to the Meissner effect. In this talk, I will present a microscopic theoretical model with local superconducting correlations above Tc, that can capture qualitatively and quantitatively the experimental results. Specifically, I will show how driving can trigger an instability of local interlayer coherence leading to exponentially enhanced currents that we argue are responsible for the magnetic field observed experimentally outside the sample. Through this lens I will explain how these experiments can be viewed as evidence for interlayer coherence at room temperature in YBCO and why theoretically this idea could be quite realistic. 
Finally, I will make a few comments on how this instability of interlayer coherence can be straightforwardly applied to excitonic bilayer systems.