An electron paramagnetic resonance study on Sm3+ and Yb3+ inKY3F10 crystals

Abstract

Electron paramagnetic resonance (EPR) spectra of Sm3+ and Yb3+ ionsin KY3F10 single crystals have been measured at X-band microwavefrequencies and low temperatures. The EPR lines have been fitted to atetragonal 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 agreementwith those calculated via crystal-field J-mixing of the first excited-statemultiplet 6H7/2 into the groundstate multiplet 6H5/2 ofSm3+ as the second-order perturbation. On the other hand, the observedg-values, (g∥ = 5.363(5), g⊥ = 1.306(2)) for Yb3+ arecoincident with those calculated via mixing in only the groundstate multiplet2F7/2 as the first-order perturbation because the first excited-statemultiplet 2F5/2 lies above ~10 000 cm-1 from thegroundstate. 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. Thedistortions of the Sm3+ and Yb3+ complexes in KY3F10 arediscussed in the term of the crystal-field Hamiltonian in comparison withLiYF4.