Strong magneto-optical enhancement and magnetic anisotropy tuning in Ce-substituted yttrium iron garnet films grown in argon and oxygen

Magneto-optical materials with low absorption enable nonreciprocal light propagation in photonic circuits. Cerium-substituted yttrium iron garnet (Ce:YIG) is particularly attractive due to its high Faraday rotation. In this paper, the effect of thickness and deposition atmosphere on the properties of Ce:YIG films is investigated. Pulsed laser deposition on (111) gadolinium gallium garnet substrates yields smooth, coherently strained films up to 220 nm thick. Growth in argon expands the out-of-plane lattice parameter, inducing perpendicular magnetic anisotropy, while oxygen-grown films exhibit in-plane magnetization. Argon-grown films show a twofold enhancement of Faraday rotation, reaching 5.0\ifmmode^\circ\else\textdegree\fi{}/\ensuremath{\mu}m at 780 nm, linked to longer electronic relaxation times in the strained lattice.