Cation distribution and its magnetic implications in gadolinium–iron garnets for an enhanced control of compensation temperature

Abstract

The precise control of the magnetic compensation temperature (θ_c) in ferrimagnetic garnets is essential for the development of cutting-edge ultrafast customizable spintronic devices. In this work we demonstrate how fine variation in stoichiometry and cation distribution in iron gadolinium garnets significanty influences θ_c. Two samples of Gd₃Fe₅O₁₁₂ garnets synthesized via a new hydrothermal method and a conventional solid-state reaction, respectively, were considered. The complex study was carried out using a complex approach combining X-ray diffraction, magnetometry, and Mössbauer spectroscopy. Atomic-scale analysis revealed with unprecedent accuracy a cationic inversion between Fe³⁺ ang Gd³⁺ at octahedral and dodecahedral sites in both samples, and their chemical compositions were determined as Gd_2.70Fe_4.76O_11.9 and Gd_2.96Fe_4.68O_11.5, respectively. These local rearrangements have been shown to have a consistent influence on θ_c (290 K and 317 K, respectively) around room temperature, emphasizing the high sensitivity of exchange interactions to internal atomic order. Results clearly illustrate the strong correlation between the processing, atomic configuration and macroscopic magnetic behavior, establishing a new paradigm for the design of garnet-based materials with tunable θ_c. The strategy for the accurate determination of cation inversion illustrated in this work exhibits great potential in guiding material innovations for next-generation spintronics.