Abstract

The observation of the nonlinear four-wave-mixing (4WM) effect in a magnetic solid is reported. The measurements were done with the antiferromagnetic FeF₂ (Neel temperature T_N = 78.6 K). Ferrous fluoride is an ionic crystal of rutile structure and has been of interest for basic studies on magnetism for many years.¹ In the present experiment the electronic transition between the ground A_1g and the excited B_1g state of the Fe²⁺ ion has been studied in detail. The generation of light at the frequency ω₄ = 2ω₁ − ω₂ by two incident laser beams at ω₁ and ω₂ is studied as a function of (ω₁−ω₂) of the sample temperature and of the laser’s polarization. The data analysis yields the energy, width, and symmetry assignment of the resonance.

© 1983 Optical Society of America