Exquisite growth control and magnetic properties of yttrium iron garnet thin films

A layer-by-layer epitaxial growth up to 227 atomic layers of ferrimagnetic insulator yttrium iron garnet (YIG) thin films is achieved on (110)-oriented gadolinium gallium garnet substrates using pulsed laser deposition. Atomically smooth terraces are observed on YIG films up to 100 nm in thickness. The root-mean-square roughness is as low as 0.067 nm. The easy-axis lies in the film plane, indicating the dominance of shape anisotropy. For (110)-YIG films, there is well-defined two-fold in-plane anisotropy, with the easiest axis directed along [001]. The Gilbert damping constant is determined to be 1.0 × 10−4 for 100 nm thick films.