Resonant two-magnon Raman scattering in cuprate antiferromagnetic insulators

Abstract

We present results of low-temperature two-magnon resonance Raman excitation profile measurements for single-layer ${\mathrm{Sr}}_{2}$Cu${\mathrm{O}}_{2}$${\mathrm{Cl}}_{2}$ and bilayer $\mathrm{Y}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{6+\ensuremath{\delta}}$ 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 triple resonance theory of Chubukov and Frenkel [Phys. Rev. Lett. 74, 3057 (1995)] and deduce information about magnetic interaction and band parameters in these materials.