Crystallographic characterization and magnetic properties of the MnIn2(1-z)Ga2zSe4 alloy system
Résumé
X-ray powder diffraction, differential thermal analysis DTA and magnetic susceptibility χ measurements were carried out on polycrystalline samples of the alloy system MnIn2(1−z)Ga2zSe4. Magnetization measurements at 2 K in magnetic fields up to 35 T were made on the MnIn2Se4 and MnGa2Se4 compounds. From the lattice parameter values, the limits of single-phase solid solution were estimated. At room temperature, the solid solutions extend over the range 0<z<0.30 for the δ-phase and from 0.75 to 1.0 for the η-phase. Values of TN, the Néel temperature, were obtained from the cusp in the χ versus T curves. Values of Curie–Weiss temperature θ were determined from the 1/χ versus T curves for the single-phase samples in each range. The magnetic results indicate that for 0<z<0.30, the Mn is randomly distributed over the cation sublattice, the phase having space group and the compound MnIn2Se4 (z=0) was found to be spin-glass, with Tg=2.75 K and θ=−94 K. The high z single phase η alloys show an ordered distribution of the Mn2+ ions on the cation sublattice and were antiferromagnetic showing ideal Curie–Weiss behavior, with TN=8 K and the Curie–Weiss temperature θ=−24 K.
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