Electronic Correlations in Multiferroic Van der Waals CuCrP2S6: Insights from X-ray Spectroscopy and DFT

The electronic structure of high-quality van der Waals multiferroic CuCrP2S6 crystals was investigated by applying photoelectron spectroscopy methods in combination with DFT analysis. Using X-ray photoelectron and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at the Cu L-2,L-3 and Cr L-2,L-3 absorption edges, we determine the charge states of ions in the studied compound. Analyzing the systematic NEXAFS and resonant photoelectron spectroscopy data at the Cu/Cr L-2,L-3 absorption edges allowed us to assign the CuCrP2S6 material to a Mott-Hubbard type insulator and identify different Auger-decay channels (participator vs spectator) during absorption and autoionization processes. Spectroscopic and theoretical data obtained for CuCrP2S6 are very important for the detailed understanding of the electronic structure and electron-correlations phenomena in different layered materials, which will drive their further applications in different areas, like electronics, spintronics, sensing, and catalysis.