An X- and Q-band Gd 3 EPR study of a single crystal of EuAlO 3: EPR linewidth variation with temperature and low-symmetry effects

Detailed electron paramagnetic resonance (EPR) studies on a single crystal of Gd 3-doped Van-Vleck compound EuAlO 3, potentially a phosphorescent/luminescent/laser material, with the Gd 3 ion substituting for the Eu 3 ion, were carried out at X-band (9.2 GHz) over the 77400 K temperature range. They provide new physical results on magnetic properties of the Eu 3 ion in a low symmetry environment. The asymmetry exhibited by the variation of the Gd 3 EPR line positions for the orientations of the external magnetic field about the Z and X magnetic axes in the ZX plane was ascribed to the existence of low, monoclinic, site symmetry, as revealed by the significant values of the spin-Hamiltonian (SH) parameters b41 and b43, estimated by fitting all the observed EPR line positions at room temperature for the orientation of the magnetic field in the magnetic ZX plane using a least-square fitting procedure. The temperature dependence of the Gd 3 EPR linewidth is interpreted to be due to the life-time broadening, caused by dynamical exchange and dipolar interactions between the impurity Gd 3 ions and the host Eu 3 ions. © 2012 Elsevier B.V. All rights reserved