Hopping-disorder-induced effects upon the two-Magnon Raman Scattering spectrum in an Antiferromagnet

Abstract

Two-magnon Raman scattering intensity is obtained for two-dimensional spin-1/2 antiferromagnets in presence of hopping disorder. A consistent mode assignment scheme is prescribed which essentially establishes a correspondence between the hopping-disordered and the pure system. It is seen that a minute amount of disorder in hopping leads to a good agreement of the Raman lineshape experimentally obtained for the copper-oxide insulators such as ${\rm {La_{2}CuO_{4}}}$. Also it is observed that a considerable asymmetry with respect to the two-magnon peak appears and the spectral intensity persisting much beyond $4J$ (where the joint magnon density of states peaks). This has been argued earlier by us [S. Basu and A. Singh, Phys. Rev. B, {\bf {53}}, 6406 (1996)] to be arising due to highly asymmetric magnon-energy renormalization because of a cooperative effect arising from local correlation in hopping disorder.