Abstract
We investigated the electronic structures of the Ruddlesden-Popper series (, 2, and ) using optical spectroscopy and first-principles calculations. As orbitals are spatially more extended than or orbitals, it has been widely accepted that correlation effects are minimal in compounds. However, we observed a Mott insulator-metal transition with a change of bandwidth as we increased . In addition, the artificially synthesized perovskite showed a very large mass enhancement of about 6, indicating that it was in a correlated metallic state.
- Received 14 July 2008
DOI:https://doi.org/10.1103/PhysRevLett.101.226402
©2008 American Physical Society