Ultrafast terahertz spectroscopy of optically excited iron-based superconductors

Iron-based superconductors display varied interaction amidst spin, charge, and structural orders leading to diverse phase diagrams. An A1g phonon mode, coherently excited in these materials by an ultrafast 800nm pump, offers a pathway to optical enhancement and suppression of material properties [1]. Short pump pulses have resulted in light-induced superconductivity above the critical temperature [2] and increase in superfluid density [3], suggesting optically controlled superconductivity. Using broadband terahertz time domain spectroscopy and ultrafast 800nm pump, we explore the light-induced non-equilibrium phenomena above and below the electronic, structural, and superconducting transitions in various iron-based superconductors.

[1] K. Kim, et al., Nature Mater. 11, 497–501 (2012).

[2] M. Mitrano, et al., Nature 530, 461–464 (2016).

[3] K. Isoyama, et al., Commun. Phys. 4, 160 (2021).