Effect of Valence Floating on the Magnetic Properties of Ca–Sn Co-Doping Y3−xCaxFe5−xSnxO12(x = 0–0.25)

First-principle calculations were used to simulate the changes in magnetic parameters and interatomic charge density in the crystal structure of yttrium iron garnet (YIG) caused by Ca–Sn co-doping. The simulation results illustrate that Ca and Sn have no spin polarization in the crystal, and the charge density among ions tends to increase with doping concentration. A solid-state reaction method was employed to prepare YIG with varying concentrations of Ca–Sn co-doping. The saturation magnetization (
$4\pi M_{s}$
) of the material shows an initial increase and then decrease as the number of doping increases. This phenomenon of increment in
$4\pi M_{s}$
at first could be accounted for the increase of the net magnetic moment of material. The reduction in
$4\pi M_{s}$
could be interpreted as the content of Fe
³⁺
(
$5~\mu \text{B}$
) decreases, while the Fe
²⁺
(
$4~\mu \text{B}$
) in the material becomes the primary portion when the concentration of doping exceeds 0.10.