We have studied the electronic structure of which undergoes a metal-insulator transition as functions of composition and temperature, by means of photoemission and inverse-photoemission spectroscopy. Spectral changes across the transition near the Fermi level (particularly within of have been interpreted as due to a “semimetallic” closure of the band gap in going from the insulating phase to the antiferromagnetic metallic phase. On the other hand, there is also composition- and temperature-dependent spectral weight transfer over a wider energy range of indicating significant correlation effects. Photoemission intensity just below remains high in the insulating phases, indicating that the carrier number is large at high temperatures and that the activation-type transport is due to the activated mobility rather than the activated carrier number.
- Received 6 April 1998
- Published in the issue dated 15 October 1998
© 1998 The American Physical Society