Fig. 3: Evolution of the optical spectrum of La3Ni2O7 under high pressure.
From: Optical properties and electronic correlations in La3Ni2O7 bilayer nickelates under high pressure
Optical conductivities σxx(ω), σyy(ω), and σzz(ω) of La3Ni2O7 (a) at ambient pressure, (b) at 30 GPa, and (c) at 50 GPa. The insets show a larger energy range. d Corresponding Fermi surfaces, colored by the Ni orbital character \(({d}_{{z}^{2}}-{d}_{{x}^{2}-{y}^{2}})/({d}_{{z}^{2}}+{d}_{{x}^{2}-{y}^{2}})\). e Energy- and k-resolved transition dipole moments at 30 and 50 GPa (in Debye; cf. Fig. 1) provide a microscopic explanation for the changes observed in the optical spectrum.
