An X- and Q-band electron paramagnetic resonance study of Mn2+ in a single crystal of NH4Cl0.9I0.1 in the temperature range 77-295 K

This work is an electron paramagnetic resonance study of the mixed ammonium chloride-iodide host crystal doped with divalent manganese. The studies presented here were carried out at X-band and Q-band microwave frequencies, and at various microwave cavity temperatures. The resonance spectrum of this crystal is described by a set of spin-Hamiltonian parameters, whose parameters are determined by fitting the various resonance line positions obtained for several angular orientations of the magnetic field relative to the crystal axes. A set of initial parameters is then determined by second-order perturbation theory. These are then rigorously evaluated by a computer subroutine using the least-squares-fitting technique. The spectra obtained through angular variation of the crystal within the static magnetic field confirm the cubic symmetry of the crystal, and the existence of three magnetically equivalent sites having their axes along the [100], [010], and [001] directions. The final set of spin-Hamiltonian parameters were interpreted using the superposition model, which is a mathematical approach used to evaluate the intrinsic parameters of the crystal, based on the sum of nearest neighbor ligand contributions