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.
@article{arxiv.1004.0042,
title = {Evidence for a correlated insulator to antiferromagnetic metal transition in CrN},
author = {P. A. Bhobe and A. Chainani and M. Taguchi and T. Takeuchi and R. Eguchi and M. Matsunami and K. Ishizaka and Y. Takata and M. Oura and Y. Senba and H. Ohashi and Y. Nishino and M. Yabashi and K. Tamasaku and T. Ishikawa and K. Takenaka and H. Takagi and S. Shin},
journal= {arXiv preprint arXiv:1004.0042},
year = {2010}
}
Comments
Submitted to Physical Review Letters (February 2010) 11 pages, 3 figures in the main text, 1 Supplementary Information