Non-equlibrium orders in solids

Schematic phase diagram of a driven paraelectric on increasing the driving field strength
Frequency of the SC gap oscillations (points) and the Bardasis-Schrieffer mode (blue line) close to s/s+id transition (red dashed line)

Works on phononic systems/ferroelectrics: [2023], [2024]

Series of works on superconductors: [2021], [2019], [2014]

Recent developments in ultrafast THz techniques enable the observation of non-equilibrium dynamics of correlated systems at scales relevant for electronic order. My particular interests are in application of these techniques to (1) stimulating phase transitions by driving phonons in insulators (2) dynamics of unconventional superconductors with competing ground states. For (1), transition to ferroelectric state driven by infrared/THz pulse was theoretically explored; more recently, a possibility of a non-equilibrium tunable density-wave order was pointed out.

For (2), some of the results are that oscillations due to the so-called Bardasis-Schrieffer modes can be observed, and, moreover, light polarization can be used to control the non-equilibrium state. Previously, it was shown that fast dynamics of superconductivity can exhibit fingerprints of competition with a charge density wave order.