Abstract
The electrical, magnetic, and structural properties of are investigated. The parent compound is a paramagnetic metal, critically close to magnetic order. We have found that, with a Ru-site doping by only a few percent of Mn, the ground state is switched from a paramagnetic metal to an antiferromagnetic insulator. Optical conductivity measurements show the opening of a gap as large as 0.1 eV, indicating that the metal-to-insulator transition is driven by the electron correlation. The complex low-temperature antiferromagnetic spin arrangement, reminiscent of those observed in some nickelates and manganites, suggests a long-range orbital order.
- Received 28 April 2005
DOI:https://doi.org/10.1103/PhysRevB.72.092404
©2005 American Physical Society