Optical Zeeman effect measurements on isolated and ferromagnetically coupled Nd3+ ions in weakly doped YVO4 crystals: evidence for lack of crystal field perturbations in ion pair interactions

Optical Zeeman effect measurements are performed at liquid helium temperatu re on Nd3+ ions in weakly doped YVO4 crystals in the range 11 350-11 390 cm (-1) of the F-4(3/2) --> I-4(9/2) neodymium transitions. This study provide s confirmation that the concentration dependent satellite lines accompanyin g the optical transitions are due to ferromagnetically coupled pairs of Nd3 + ions in undistorted Y3+ sites of D-2d point site symmetry. Nonlinear Zeem an splittings are observed in the range of experimental magnetic fields. Th ese splittings are compared with those simulated from crystal field calcula tions by introducing the Zeeman Hamiltonian into the secular determinant be fore diagonalization. A reasonably good agreement between the calculated an d experimental g-values is obtained, confirming that the exchange coupled n eodymium pairs experience no crystal field perturbations.