The Raman scattering investigation of low-energy electronic excitations features of the terbium ion in the KTb(WO4)2 single crystal

Raman light scattering in the KTb(WO4)2 single crystal is investigated in the frequency range of 3-950 cm-1 at 5 K. The ground multiplet 7F6 of Tb3+ ion is splitting by the crystal field with symmetry C2, and all the multiplet components are detected. It is founded that the first excited electronic quasi doublet consists of two singlet levels of different symmetry, and it is separated from the ground quasi doublet by the gap of ∼ 75 cm-1. The behavior of all detected levels is investigated in external magnetic fields H perpendicular C2 and H || C2. The factors of spectroscopic splitting are determined for the ground and excited levels of the Tb3+ ion in the KTb(WO4)2 crystal. The experimental data support the view that at low temperatures the case of Ising anisotropy is realized, and the crystal under study should be considered as a system of two-level magnetic ions.