An electron paramagnetic resonance study on Sm3+ and Yb3+ in KY3F10 crystals

Electron paramagnetic resonance (EPR) spectra of Sm3+ and Yb3+ ions in KY3F10 single crystals have been measured at X-band microwave frequencies and low temperatures. The EPR lines have been fitted to a tetragonal spin Hamiltonian to determine effective g-values (g, g). The observed g-values, (g=0.714(2), g=0.11(1)), for Sm3+ are in agreement with those calculated via crystal-field J-mixing of the first excited-state multiplet 6H7/2 into the groundstate multiplet 6H5/2 of Sm3+ as the second-order perturbation. On the other hand, the observed g-values, (g=5.363(5), g=1.306(2)) for Yb3+ are coincident with those calculated via mixing in only the groundstate multiplet 2F7/2 as the first-order perturbation because the first excited-state multiplet 2F5/2 lies above ~10 000 cm-1 from the groundstate. The groundstate eigenfunctions of Sm3+ and Yb3+ obtained from the EPR results are close to those calculated from a C4v symmetry crystal-field analysis applied to their optical transitions. The distortions of the Sm3+ and Yb3+ complexes in KY3F10 are discussed in the term of the crystal-field Hamiltonian in comparison with LiYF4.