Zeeman splitting features of electronic states of rare earth ions in TbF3 crystal

Optical absorption and photoluminescence (PL) spectra in the TbF3 crystals have been studied within the visible spectral range at the temperature of 90 K. Measurements of luminescence excitation spectra (LES) were carried out at temperatures of 25 and 300 K using the synchrotron radiation source. By comparison of PL and absorption spectra related to the optical transitions between Stark sublevels of 5D4 and 7F6 multiplets of Tb3+ ion at T = 90 K we can draw a diagram of the optical transitions between Stark sublevels and define their energies and positions in combining in optical transitions multiplets. It has been found that effect of the external magnetic field, which is parallel to a axis of the orthorhombic crystal, results in reduction of initial splitting of 10.7 cm−1 of well resolved doublet line of 7F6 → 5D4 absorption band observed in π polarization near 20,675 cm−1 with linear-polarized light propagated parallel to c crystallographic axis. At the same time in another experimental geometry, in which the external magnetic field is perpendicular to the a-b plane of the TbF3 crystal, an absorption line at ~20,730 cm−1 has the Zeeman splitting, which increases with the increase of magnetic strength. Such non-trivial behavior of the Zeeman effect in the TbF3 crystal is explained by peculiar features of magnetization of non-Kramers rare earth ions in crystal surroundings with CS symmetry, which is typical for crystallographic structure of trifluoride. •Diagram of 5D4. → 7F6 transitions between Stark sublevels is made•Onset of PL bands of forbidden 4f.→ 4f transitions 5D4 → 7F6 is observed•Magnetic field results in reduction of initial splitting of 7F6. → 5D4 line•If the field is perpendicular to the a-b plane the quasi doublet does not split.