EPR of Gd³⁺-Doped La_0.9Nd_0.1F₃Crystal: Spin-Phonon Interactions and Spin-Lattice Relaxations

Abstract

The X-band EPR study of Gd 3+ -doped Lao .9 Ndo . 1 F3 single crystal in the temperature range 4.2-295 K is carried out in order to investigate crystal field effects, the Gd3 + spin-phonon interactions, as well as Gd 3 + and Nd3 + spin-lattice relaxation times. The local distortions at 4.2 K of the positions of the eight F -ions surrounding the Gd 3 + ion in the Lao.9Nd0.1 F3 crystal were determined from comparison of the theoretical with the experimental spin-Hamiltonian parameters. The spin-phonon interactions can be described by the Einstein model, which better characterizes the behavior of paramagnetic centers in LaF3 and Lao,9Ndo.1 F3 crystals than the Debye model. It is suggested, from the rotational invariance mechanism for phonon-induced contributions to spin-Hamiltonian parameters, that the rotational contributions are much smaller than those from the strain.