Fig. 4
From: Imaging the nanoscale phase separation in vanadium dioxide thin films at terahertz frequencies
Spectra at different temperatures around Tc, calculated from DMFT for the dimer Hubbard model. Spectra calculated with parameters t⊥ = 0.2, U = 3.1 (a–c) and t⊥ = 0.5, U = 2.405 (d–f) as a function of energy normalized to the half-bandwidth D. The temperatures (normalized to Tc) of each curve for small t⊥/U (a–c) are shown to the left of panel (a). The temperatures used for large t⊥/U (d–f) are shown to the left of panel (d). The local density of states (LDOS) at different temperatures as a function of energy is shown for small t⊥/U (a) and large t⊥/U (d). The black line is the LDOS at T = 0. The sharp peak in the T = 0 LDOS in (d) is due to the formation of an intra-dimer singlet at very low temperatures (see text for details). The real part of the optical conductivity at different temperatures is shown for small t⊥/U (b) and large t⊥/U (e). All conductivities are normalized to the DC conductivity at the highest temperature shown (i.e., the DC conductivity of the metallic state). The calculated near-field signal at different temperatures as a function of frequency is shown for small t⊥/U (c) and large t⊥/U (f). The vertical gray lines in all figures indicate the THz (dashed) and MIR (dotted) frequencies used for calculating histograms in Fig. 5
