Fig. 3: Mott insulator (MI) to charge-transfer insulator (CTI) transition.
From: Incommensurate charge super-modulation and hidden dipole order in layered kitaev material α-RuCl3
a Bias-resolved dI/dV maps taken on the same region of 3-MLs α-RuCl3 (Vbias = 900 mV, Iset = 1 nA). Orbital textures corresponding to the Ru sites (light blue dots) are detected at the edge of UHB (180–300 mV). In contrast, the negative bias side displays the textures of Cl 3p orbitals (green dots). b A comparison of averaged dI/dV spectra taken on the Ru and Cl sites reveals enhanced occupied states and distinct dip-humps at Cl sites (Vbias = 800 mV, Iset = 800 pA). Inset schematically shows the configuration and pattern of Cl 3p orbitals. c Schematic DOS (density of states) from MI to CTI when the Cl 3p orbitals enter the Mott gap of Ru 4d electrons with changing thickness (layer number). U(L)HB is an abbreviation of upper (lower) Hubbard band; U is the Coulomb interaction and △ denotes the charge transfer gap.
