Abstract
Optical absorption at the insulating gap in the parent phase of cuprate superconductors shows a broad exciton-like peak near 1.7 eV, followed by a gradual decrease in absorption persisting 1 eV above the gap. By using ultraviolet laser lines to excite Raman spectra, we have found a Raman peak 0.2 eV below the first absorption peak in insulating cuprates. The Raman peak is much narrower than the absorption peak and hasA 2g symmetry. We assign it to an exciton consisting of a hole transition from Cu\(d_{x^2 - y^2 } \) to a linear combination of Cud xy and nearest neighbor Op π orbitals. We have also studied the resonance Raman profile for two-magnon Raman scattering in the same samples. We find a sharp resonance feature at about 2.7 eV, and little Raman intensity for photon energies at the 1.7 eV absorption peak. The state created at the peak must therefore be an inappropriate intermediate state for the double spin-flip Raman process.
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References
S. Uchida, T. Ido, H. Takagi, T. Arima, Y. Tokura, and S. Tajima,Phys. Rev. B 43, 7942 (1991); S. L. Cooper, D. Reznik, A. Kotz. M. A. Karlow, R. Lui, M. V. Klein, W. C. Lee, J. Giapintakis and D. M. Ginsberg,Phys. Rev. B 47, 8233 (1993).
For a review see R. R. P. Singh,Comments Cond. Matter. Phys. 15, 241 (1991).
K. B. Lyons. P. A. Fleury, L. F. Schneemeyer, and J. V. Waszczak,Phys. Rev. Lett. 60, 732 (1988).
M. Yoshida, S. Tajima, N. Koshizuka, S. Tanaka, S. Uchida, and T. Itoh,Phys. Rev. B 46, 6505 (1992).
B. S. Shastry and B. I. Shraiman,Phys. Rev. Lett. 65, 1068 (1990);Int. J. Mod. Phys. B 5, 365 (1991).
S.-W. Cheong, J. D. Thompson, and Z. Fisk,Physica C 158, 109 (1989).
J. P. Rice and D. G. Ginsberg,J. Cryst. Growth 109, 432 (1991); W. C. Lee and D. M. Ginsberg,Phys. Rev. B 44, 2815 (1991).
Ran Liu, M.V. Klein, D. Salamon, S. L. Cooper, W. C. Lee, S.-W. Cheong, and D. M. Ginsberg,Proc. of Conf. on Spectroscopies in Novel Superconductors, Santa Fe, March, 1993, F. Mueller, ed.,J. Phys. Chem. Solids,54, 1347 (1993).
Ran Liu, D. Salamon, M. V. Klein, S. L. Cooper, W. C. Lee, S.-W. Cheong, and D. M. Ginsberg,Phys. Rev. Lett. 71, 3709 (1993).
D. R. Wake, unpublished preprint.
J. F. Annett, R. M. Martin, A. K. McMahan, and S. Satpathy,Phys. Rev. B 40, 2620 (1989).
P. E. Sulewski,Phys. Rev. Lett. 65, 3864 (1991).
D. V. Khveshchenko and P. B. Wiegmann, preprint. See P. Wiegmann,Prog. Theor. Phys. Suppl. 107, 243 (1992).
J. D. Perkins, J. M. Graybeal, M. A. Kastner, R. J. Birgenau, J. P. Falck, and M. Greven,Phys. Rev. Lett. 71, 1621 (1993).
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Klein, M.V., Liu, R., Salamon, D. et al. New features of the Mott-Hubbard insulator gap of parent HTS compounds found by resonance Raman scattering and UV-excited ordinary Raman scattering. J Supercond 7, 429–433 (1994). https://doi.org/10.1007/BF00724583
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DOI: https://doi.org/10.1007/BF00724583