Review: the plasmonic phase-change material In₃SbTe₂ for nanophotonics [Invited]

Metasurfaces have evolved as versatile platforms for tailoring light-matter interactions. Combining metasurfaces with active materials such as phase-change materials (PCMs) promises reconfigurable modifications of the metasurface functionalities. Conventional PCMs enable non-volatile resonance tuning based on a change in refractive index due to positive permittivity values in the amorphous and crystalline phases. The recently introduced plasmonic PCM In 3 SbTe 2 (IST) features a plasmonic crystalline phase with negative permittivity in the entire infrared spectral range. In contrast to conventional antenna resonance tuning based on a change in refractive index, IST allows for directly reconfiguring the shapes and sizes of the antennas to modify electromagnetic resonances accordingly. More importantly, IST features a platform for direct programming of functional metasurfaces without cumbersome fabrication techniques to tailor emissivity, polariton propagation or infrared beam-shaping. This review highlights recent work in the field of active nanophotonics with the plasmonic PCM IST and provides further research directions establishing IST as a versatile nanophotonic platform.