Resonant two-magnon Raman scattering in cuprate antiferromagnetic insulators

We present results of low-temperature two-magnon resonance Raman excitation profile measurements for single-layer Sr{sub 2}CuO{sub 2}Cl{sub 2} and bilayer YBa{sub 2}Cu{sub 3}O{sub 6+{delta}} antiferromagnets over the excitation region from 1.65 to 3.05 eV. These data reveal composite structure of the two-magnon line shape and strong nonmonotic dependence of the scattering intensity on excitation energy. We analyze these data using the {ital triple} {ital resonance} theory of Chubukov and Frenkel [Phys. Rev. Lett. {bold 74}, 3057 (1995)] and deduce information about magnetic interaction and band parameters in these materials. {copyright} {ital 1996 The American Physical Society.}