Table 1.

Key attributes and challenges for leading magnetic materials for magnonic applications. Information sources: YIG [39,40,41], Co₂₅Fe₇₅ [18,42], and MgAl_0.5Fe_1.5O₄ [19].

	Thin Film/Substrate	(YIG)Y3Fe5O12/ Gd3Ga5O12 (GGG)	Co25Fe75/ Si/SiO2	MgAl0.5Fe1.5O4/ MgAl2O4
Parameters
Gilbert damping constant		α ≈ 6.7 × 10−5	α ≈ 2.1 × 10−3	α ≈ 1.5 × 10−3
Magnon propagation length		Several cm	(21 ± 1) µm	(0.6–0.9) µm
Magnetostatic exchange length		~17.6 nm	~3.4 nm	~20.5 nm
Thin film fabrication		Liquid phase epitaxy on single crystal (111) Gd3Ga5O12 with PbO-B2O3 flux 927 °C.	Sputter deposited on Si/SiO2 substrates at ambient temperature. Polycrystalline films, no post-deposition processing required.	Pulsed laser deposition at 450 °C on MAO substrates. Epitaxial growth required.
Challenges for magnonic applications		Growth is not CMOS compatible. Expensive substrates.	Reduce extrinsic factors that increment the intrinsic damping parameter.	PLD fabrication is challenging to scale up. Alternative substrates. Low Ms.