Self-Phase Modulation and Stimulated Raman Scattering from Magnon-Pair Scattering and Electronic Kerr Index in Antiferromagnetic Perovskite KNiF₃ Crystal

Spectral broadening and stimulated Raman scattering from Magnon-pair scattering in antiferromagnetic KNiF₃ bulk crystal is observed from 90 femtosecond 532 nm laser pulses at different temperatures below and above Neel temperature from 50 K to 300 K at different laser beam powers. Below the Neel temperature, considerable enhancement of the frequency broadened intensity is observed, which is attributed to the magnetic part of Kerr nonlinear index from the magnon spin-dependent part of third-order susceptibility.