The origin of enhanced magnetodielectric effect in Y3-xYbxFe5O12 ceramics

In this work, dielectric and magnetic behaviors, as well as magnetodielectric (MD) effect of Yb-substituted yttrium iron garnet (Y3-xYbxFe5O12) ceramics, have been studied systematically. Three dielectric relaxations are detected from the temperature spectrums, which can be attributed to the charge carries hopping between Fe2+ and Fe3+, inhomogeneous structure, and conduction, respectively. All the samples exhibit ferrimagnetic behaviors at room temperature and the saturation magnetization (Ms) increases first and then decreases with increasing Yb-substitution. The variation of Ms can be viewed as a comprehensive effect of superexchange interaction of Fe1-O-Fe-2 and double exchange interaction between Fe2+ and Fe3+ ions. The room-temperature MD effect of Y3-xYbxFe5O12 ceramics measured at 15 kOe and 1 MHz are -1.11%, -1.33%, -2.04%, -1.48%, and -1.57%, for x = 0, 0.5, 1, 2, and 3, respectively. With the analysis of XPS spectra, the origin of enhanced MD effect has been investigated, and it is mainly caused by the response of local dipoles (Fe2+- Fe3+) under applied magnetic field. Published by AIP Publishing.