Bulg. J. Phys. vol.30 no.1-2 (2003), pp. 45-51

The 0-M-O Triatomic Molecule: Basic Unit of Cuprates and Manganates

S.G. Tsintsarska1, M.D. Ivanovich2, M. Georgiev2, A.D. Gochev3
1Central Laboratory for Photoprocesses, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
2Institute of Solid State Physics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
3Chemical Abstract Service, Columbus OH 43221, USA
Abstract. The O(oxygen)-M(metal)-O(oxygen) molecule is a basic unit of high-temperature super-conducting cuprates and colossal magnetoresistance exhibiting manganates. This molecule can be regarded either as an element of a linear chain or as an ingredient of the corresponding cuprate or manganate lattice. The symmetry of the unit being different in the two approaches, group theory imposes different limitations on conceivable vibrational modes and atomic orbitals that control its transport and optical properties. We now calculate the electron hopping energies along Cu(P)-O(A) bonds, sites for nonlocal electron-vibrational mode coupling. We find the electric transport along the O(A)-Cu(P)-O(A) molecule dominated by scattering from bond polarons which is reflected in the two-branch character of the temperature dependence of its electric resistance.

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