We investigate the electronic structure of chromium nitride (CrN) across the first-order magnetostructural transition at TN∼286K. Resonant photoemission spectroscopy (PES) shows a gap in the 3d partial density of states at the Fermi level and an on-site Coulomb energy U∼4.5eV, indicating strong electron-electron correlations. Bulk-sensitive high-resolution (6 meV) laser PES reveals a clear Fermi edge indicating an antiferromagnetic metal below TN. Hard x-ray Cr 2p core-level PES shows T-dependent changes across TN which originate from screening due to coherent states as substantiated by cluster model calculations using the experimentally observed U. Electrical resistivity confirms an insulator above TN (Eg∼70meV) becoming a disordered metal below TN. Thus, CrN transforms from a correlated insulator to an antiferromagnetic metal, coupled to the magnetostructural transition.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)