Moderate Gilbert damping and perpendicular magnetic anisotropy in Yb3Fe5O12 films

The realization of perpendicular magnetic anisotropy (PMA) in a rare-earth iron garnet composition has the potential to open up the field of spintronics and magnonics. In this study, we introduce ${\mathrm{Yb}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$ (YbIG) as an iron garnet thin film candidate exhibiting PMA. We have grown highly epitaxial YbIG films on (111) oriented ${\mathrm{Gd}}_{3}{\mathrm{Ga}}_{5}{\mathrm{O}}_{12}$ (GGG) substrates. Detailed growth, structural, magnetic, and dynamical properties of the YbIG/GGG(111) thin films are reported. We reveal a transition from the in-plane (IP) to out-of-plane (OOP) magnetic easy-axis as the film thickness decreases. The gradual increase in the OOP anisotropy field from 18 Oe to 1100 Oe with decreasing film thickness is consistent with the observed variation of the OOP lattice parameter due to epitaxial strain. Further, sixfold symmetry in the IP angular variation of resonance field ${\mathrm{H}}_{r}$ reveals the presence of a significant contribution of the second-order magnetocrystalline anisotropy (${\mathrm{K}}_{2}$). The damping factor $\ensuremath{\alpha}\ensuremath{\sim}{10}^{\ensuremath{-}2}$ is comparable to TmIG, which has been proposed as a promising material for application due to PMA. These findings present YbIG as a potential contender for spintronic and magnonic applications because of its PMA with moderate $\ensuremath{\alpha}$.