Ultrafast Laser-Driven Dynamics in Metal-Insulator Interface

Mott insulators are examples of strongly correlated solid-state systems with complex properties resulting from the many-body physics at play. Here, we probe the ultrafast dynamics of metal-insulator (MI) interfaces by coupling a free chain to the Mott insulator. We study the effect of an increased interfacial coupling on the electronic and magnetic properties in the insulator, the underlying microscopic mechanisms at play, and the resulting effect on the optical response in the high-harmonic spectrum.

We show that an increased coupling to the metal leads to an enhanced response, where the threshold field is significantly reduced, with dielectric breakdown occurring at much weaker fields. This is due to charge fluctuations induced by the metal, which result in a dramatically increased correlation length in the insulator. This is supported by independent DMRG calculations. The enhanced response also shows up clearly in the HHG spectrum, where the low-order harmonic intensity is increased by two orders of magnitude. We further examine a different phase of the system, a correlated band insulator, given by much stronger interfacial coupling. The response of this phase is inherently different from the MI interface; marked by a much weaker optical response, and an inverted dependence on the strength of electronic repulsions.

The applications of the results above are numerous, ranging from the advancement of memristor technology to the use of HHG as a spectroscopic probe, and for material characterization and identification.