ELECTRONIC RAMAN SCATTERING IN FeF2

Using an argon ion laser, optical Raman scattering associated with an electronic crystal field state of FeF2 has been studied, A broad spectrum has been observed, dominated at low temperatures by an intense line 28 cm−1 broad, located at 1082 cm−1. The exact nature of this Raman excitation is not well understood at present. The Raman line intensity is strongly dependent on magnetic ordering, and its spectrum is unaffected by magnetic fields up to 80 kOe, with H ∥ c. The 1082 cm−1 feature is also observed as a magnetic dipole infrared absorption close to the stronger magnetic dipole transition at 1115 cm−1 reported previously. Because of its Raman polarization rules and its energy, the excitation seems to be associated with the low‐lying B1g (paramagnetic group) manifold arising from the orthorhombic splitting of the 5T2g cubic field ground state of Fe2+.