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Effect of pressure on optical excitations in semiconducting MBa/sub 2/Cu/sub 3/O/sub 6/ (M = Y,Sm,Gd)

Journal Article · · Phys. Rev. B: Condens. Matter; (United States)
We report optical reflectance measurements in the 0.5--4-eV region for ceramic samples of MBa/sub 2/Cu/sub 3/O/sub 6/ (M = Y, Sm, Gd) as a function of pressure up to 34 GPa. Two distinct optical transitions at 1.75 and 2.6 eV can be identified in the visible region. These transitions show only a weak shift with pressure (pressure coefficients dE/dP = -2 and 10 meV/GPa, respectively) or rare-earth substitution. Based on the strength of these transitions, their pressure behavior, and the observation of a similar optical response for La/sub 2/CuO/sub 4/, we assign the 1.75-eV excitation in MBa/sub 2/Cu/sub 3/O/sub 6/ as due to the O(p)-Cu(d) charge-transfer-gap in the two-dimensional Cu-O network.
Research Organization:
Max-Planck-Institut fuer Festkoerperforschung, D-7000 Stuttgart 80, Federal Republic of Germany
OSTI ID:
7090308
Journal Information:
Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 38:10; ISSN PRBMD
Country of Publication:
United States
Language:
English