Deciphering temperature-driven magnetic transformations and canting mechanism in the Y3Fe5-xCdXO12 compound: a coupled molecular field and phenomenological analysis.

Abstract

In this study, the Y3Fe5-xCdxO12 compounds were synthesized via the sol-gel method for Cd doping levels of x = 0.00, 0.01, 0.03, 0.05, and 0.07. X-ray diffraction analysis revealed that the single YIG phase is maintained at 100% for x = 0.00 and 0.01, while minor secondary CdO phases are detected at higher doping levels, 0.13% for x = 0.03, 1.17% for x = 0.05, and 4.42% for x = 0.07. Concurrently, the lattice parameter increased from 12.3808 A (x = 0.00) to 12.4012 A (x = 0.07), and the unit cell volume expanded from 1897.8 A3 to 1907.4 A3, reflecting the incorporation of some Cd2+ ions in place of Fe3+. Magnetic measurements performed between 100 K and 300 K indicated a systematic decrease in saturation magnetization with increasing temperature. The experimental Ms values, determined by fitting the high-field data with the Law of Approach to Saturation, were quantitatively reproduced using a coupled theoretical model that integrates Dionne's modifications to the molecular field coefficients with a phenomenological analysis of cation distribution. The relevance of coupling the models lies in the dependence of the molecular field coefficients on cation distribution, which is critical for accurately calculating the saturation magnetization and understanding the underlying physical mechanisms. Remarkably, considering magnetic moment canting resulted in a maximum relative deviation of only 7.50% from experimental values, compared to discrepancies as high as 38.7% when assuming a collinear arrangement of magnetic moments. The preferential occupancy of Cd2+ in octahedral sites, with an occupation probability seven orders of magnitude greater than in tetrahedral sites, further underlines its role in modulating the net magnetic moment.