Correlated Plasmonic Excitation in Twisted Nematic Plasmonic Superlattices

Abstract

Superlattices with twisted configurations, such as moire lattices, have recently been extensively exploited for their unique electronic, magnetic, and optical properties. One remarkable feature of nanoscale twisted superlattices is the distinct lattice symmetries and the continuous phase transitions between periodic or aperiodic phases, representing a unique opportunity to study many emerging physical phenomena. Here, we report a correlated light and matter interaction between the collective polarization effect of nematic plasmonic superstructures and the plasmonic excitation of individual constituent nanorods in reconfigurable twisted plasmonic superlattices. Using hybrid Fe3O4 and Au nanorods as building blocks, we assembled plasmonic nematic liquid crystals with unidirectionally aligned nanorods, which could be further assembled into moire plasmonic lattices through a vertical stacking assembly method. A twist angle dependent plasmonic excitation is recognized in the twisted bilayer of two plasmonic superlattices, featuring enhanced transverse and longitudinal plasmonic excitation at a twisting angle of 0 degree and 90 degree, respectively. Such correlated plasmonic excitation in twisted plasmonic superstructures is induced by the correlation between the collective polarization effect of the liquid crystal phases and the anisotropic plasmonic excitation of individual nanorods. The magnetic orientation control allows for precise alignment of hybrid Fe3O4 and Au nanorods in polymer substrates and enables the coding of nematic domains and plasmonic patterns in each sublattice. The correlated plasmonic excitation and light polarization create reconfigurable photonic moire superlattices with well-defined domain colors, feature sizes, periodicities, symmetries, and dimensions determined by twist angles and displacements in the twisted plasmonic lattices.