Abstract
Common optical absorption features are observed near 0.5 eV in four undoped single-crystal copper oxides: La2CuO4, Nd2CuO4, Pr2CuO4, and Sr2CuO2Cl2. These absorption bands are shown to be weakly electric dipole allowed excitations of the CuO2 layers. The features are ascribed to an exciton near 0.4 eV, probably of crystal field origin, with strong multimagnon sidebands. Our observations provide an important basis for understanding the doped materials.
Original language | English (US) |
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Pages (from-to) | 1621-1624 |
Number of pages | 4 |
Journal | Physical review letters |
Volume | 71 |
Issue number | 10 |
DOIs | |
State | Published - 1993 |