Evidence for a correlated insulator to antiferromagnetic metal transition in CrN

Abstract

We investigate the electronic structure of Chromium Nitride (CrN) across the first-order magneto-structural transition at T_N ~ 286 K. Resonant photoemission spectroscopy shows a gap in the 3d partial density of states at the Fermi level and an On-site Coulomb energy U ~ 4.5 eV, indicating strong electron-electron correlations. Bulk-sensitive high resolution (6 meV) laser photoemission reveals a clear Fermi edge indicating an antiferromagnetic metal below T_N. Hard x-ray Cr 2p core-level spectra show T-dependent changes across T_N which originate from screening due to coherent states as substantiated by cluster model calculations using the experimentally observed U. The electrical resistivity confirms an insulator above T_N (E_g ~ 70 meV) which becomes a disordered metal below T_N. The results indicate CrN transforms from a correlated insulator to an antiferromagnetic metal, coupled to the magneto-structural transition.

Submitted to Physical Review Letters (February 2010) 11 pages, 3 figures in the main text, 1 Supplementary Information

References in corpus (3)

• Localized Superconductivity in the Quantum-Critical Region of the Disorder-Driven Superconductor-Insulator Transition in TiN Thin Films
• Bulk screening in core level photoemission from Mott-Hubbard and Charge-Transfer systems
• Tunneling studies in a homogeneously disordered s-wave superconductor: NbN

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• The Rise of Refractory Transition-Metal Nitride Films for Advanced Electronics and Plasmonics
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• Thermoelectric properties and electronic structure of Cr(Mo,V)Nx thin films studied by synchrotron and lab-based X-ray spectroscopy
• Synthesis of functional nitride membranes using sacrificial water-soluble BaO layers