Dy3TaO7, A stoichiometric spin glass and the effect of disorder via chemical substitution in the Dy3−xYxTaO7 (0 ≤ x ≤ 3) solid solution

Abstract

In this work, we present both structural and magnetic (DC magnetization and AC susceptibility) studies of the Dy3−xYxTaO7 solid solution. The structural characterization of samples was performed by Rietveld refinements of the X-ray diffraction data. All compounds crystallized in a weberite-related structure in the orthorhombic C2221 space group (No. 20); the variations of the lattice parameters obey the Vegard´s law in the whole range of composition. DC magnetic measurements of the Dy3−xYxTaO7 system showed a Curie-Weiss paramagnetic behaviour, with antiferromagnetic interactions at T>150K. Below 3K a spin glass behaviour in the 0 ≤ x ≤ 1 range of the solid solution was observed. The stoichiometric Dy3TaO7 compound showed spin glass behaviour although there is no evidence of structural disorder. For some Y3+ doped compounds (x = 0.33, 0.66 and 1.0), chemical disorder reduced the freezing temperature (Tg) values with a ×1/3 dependence. Cole-Cole analysis of the AC magnetic field response showed similar phenomenological parameters for the stoichiometric (x = 0) and the Y3+ doped compounds with spin glassiness, suggesting an analogous mechanism for these compounds. For the Dy3−xYxTaO7 system, in which the spin glass behaviour seems to exhibit a critical concentration, a magnetic phase diagram is proposed.