Abstract
Measurements are reported of the transmission of single crystals of containing no excess oxygen. Several weak absorption bands are observed in the range 0.15–2 eV arising from magnetic and crystal-field excitations. The lowest-energy band, at 0.25 eV, is quantitatively described by a recent theory for phonon-assisted creation of a virtual bound state of two magnons. However, unlike , no higher-energy sidebands are detected, suggesting that the broad, structured absorption seen clearly in between ∼0.4 and 1 eV results from sidebands to crystal-field excitons as previously proposed.
- Received 26 July 1995
DOI:https://doi.org/10.1103/PhysRevB.52.R9863
©1995 American Physical Society