Measurement of collective excitations in VO2 by resonant inelastic x-ray scattering

Author(s): He, H; Gray, AX; Granitzka, P; Jeong, JW; Aetukuri, NP; Kukreja, R; Miao, L; Breitweiser, SA; Wu, J; Huang, YB; Olalde-Velasco, P; Pelliciari, J; Schlotter, WF; Arenholz, E; Schmitt, T; Samant, MG; Parkin, SSP; Durr, HA; Wray, LA | Abstract: © 2016 American Physical Society. Vanadium dioxide is of broad interest as a spin-12 electron system that realizes a metal-insulator transition near room temperature, due to a combination of strongly correlated and itinerant electron physics. Here, resonant inelastic x-ray scattering is used to measure the excitation spectrum of charge and spin degrees of freedom at the vanadium L edge under different polarization and temperature conditions, revealing excitations that differ greatly from those seen in optical measurements. These spectra encode the evolution of short-range energetics across the metal-insulator transition, including the low-temperature appearance of a strong candidate for the singlet-triplet excitation of a vanadium dimer.