MOMENTUM-DEPENDENT CHARGE-TRANSFER EXCITATIONS IN SR2CUO2CL2 ANGLE-RESOLVED ELECTRON-ENERGY-LOSS SPECTROSCOPY

Citation
Yy. Wang et al., MOMENTUM-DEPENDENT CHARGE-TRANSFER EXCITATIONS IN SR2CUO2CL2 ANGLE-RESOLVED ELECTRON-ENERGY-LOSS SPECTROSCOPY, Physical review letters, 77(9), 1996, pp. 1809-1812
Citations number
21
Categorie Soggetti
Physics
Journal title
ISSN journal
00319007
Volume
77
Issue
9
Year of publication
1996
Pages
1809 - 1812
Database
ISI
SICI code
0031-9007(1996)77:9<1809:MCEISA>2.0.ZU;2-F
Abstract
Electron-hole pair excitations in the insulating cuprates Sr2CuO2Cl2 w ere investigated by angle-resolved electron energy loss spectroscopy. The optically allowed and optically forbidden transitions were observe d to be strongly anisotropic in the Cu-O-2 plane. The former show a la rge energy dispersion similar to 1.5 eV along [110], and the latter ap pear at a higher energy position (similar to 4.5 eV) only along [100], but not along [110]. We interpret these results as transitions involv ing excitons. A small exciton model is examined to explain both the ob served features.