Events in Physics

Controlling the structural and electronic properties of solids with THz lasers has opened up tantalizing prospect in ultrafast materials science. In contrast to optical frequencies it enables mode-selective driving of vibrational excitations relevant for the establishment of various broken-symmetry states. In particular so-called light-induced superconductivity has been observed in several materials ranging from cuprates to alkali-doped fullerenes. Motivated by experiments on driven infrared active molecular vibrations in organic materials, I will discuss the effect of a finite frequency ω modulation of on-site energies in the Hubbard model with a checkerboard spatial periodicity. In particular we focus on the strong-coupling limit U >> t of the doped Hubbard model where the effective t-J Hamiltonian is applicable and super-exchange pairing can occur. Through a Floquet analysis, in the physically relevant regime where U >> ω and ω >> t, J, we show that this driving causes a substantial suppression of the electronic hopping t, while leaving the bare super-exchange interaction J unchanged. This suggests that electrons can be slowed down enough in the out-of-equilibrium state to allow the normally subordinate super-exchange interaction to become dominant, and thus favour nearest-neighbour pairing. I will show that this leads to a compelling new pathway to engineering light-induced superconductivity in strongly correlated quantum materials.