Time-resolved observation of magnon renormalization effects in Cr/sub 2/O/sub 3/

Summary form only given. In the last decade time resolved nonlinear optical spectroscopy (TR-NLOS) has revealed a wealth of information on many body effects in semiconductors and their heterostructures. Surprisingly TR-NLOS techniques have not been thoroughly applied to strongly correlated materials, where Coulomb interaction produces zero-order effects, and therefore play an even more dominant role in many physical properties. In this contribution we present the first TR-NLOS investigation of magnon dynamics in a strongly correlated antiferromagnetic insulator, Cr/sub 2/O/sub 3/. We have observed a novel nonlinear optical effect associated with the occupation dependence of the magnon dispersion relation, which presents the opportunity to optically manipulate and study magnetic excitations in strongly correlated insulators.