Abstract
The microscopic mechanism of the metal-insulator transition is studied by orbital-resolved NMR spectroscopy in a prototype of the quasi-one-dimensional system . We uncover that the transition involves a site-selective orbital order lifting twofold orbital degeneracy in one of the two chains. The other chain leaves paramagnetic moments on the singly occupied orbital across the transition. The two chains respectively stabilize an orbital-assisted spin-Peierls state and an antiferromagnetic long-range order in the ground state. The site-selective Mott transition may be a source of the anomalous metal and the Mott-Peierls duality.
- Received 12 November 2014
DOI:https://doi.org/10.1103/PhysRevLett.114.166403
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