Magnetic resonance studies of Dy 3+ and Er 3+ in lanthanum nicotinate dihydrate

Abstract

Electron paramagnetic resonance (EPR) measurements have been made on Dy 3+ and Er 3+ in lanthanum nicotinate dihydrate (LaND) single crystals, for comparison with the information described in the previous paper about single crystals of DyND and ErND. For both DyND and ErND, as for TmND, the measurements were found to be consistent with a ground state with a large amplitude of M j ═ ± J , an almost Ising-like g -matrix, and a purely magnetic dipole-dipole interaction between nearest neighbour (NN) Ln 3+ ions, where Ln is either Dy or Er. In contrast, for Ln 3+ dilutely substituted into LaND, although the g -matrix has one principal value much larger than the other two, the principal direction is different from that for LnND. EPR in crystals of LaND containing between 0.01 and 0.1 mole fraction of Ln shows that isolated ions have a g -matrix very similar to that in more dilute crystals, and NN pairs have a g -matrix similar to that for LnND and a purely magnetic dipole-dipole interaction. Hence, the Kramers ions Dy 3+ and Er 3+ are seen to exhibit the same features as were found for the non-Kramers ions Tb 3+ and Tm 3+ in the lanthanide nicotinate dihydrates.