Figure 4: Optical and electrical properties of the superlattice nanosheets.

(a) DSC thermogram, (b) temperature-dependent FTIR spectra indicate that the superlattice nanosheets experience a first-order phase transition as temperature varies. (c) The magnified FTIR spectra. The temperature-dependent FTIR spectra also imply the optical switching of the superlattice nanosheets in middle-wavelength IR regions. (d) Temperature-dependent Raman spectra of the obtained superlattice.