Stress-Induced Perpendicular Magnetization in Epitaxial Iron Garnet Thin Films

We have grown pseudomorphic Tm3Fe5O12 films (46-350 nm in thickness) with perpendicular magnetization on (111) Gd3Ga5O12 substrates. Among various garnets, Tm3Fe5O12 is selected because of a negatively large magnetostriction constant to overcome strong shape anisotropy in very thin films. A stress-induced anisotropy field as large as +25 kOe is estimated by calculation under a moderate in-plane tensile strain of +0.49%. The magnetization hysteresis loop and magnetic domain structure indicate the perpendicular easy axis. The domain size (W) in its maze pattern varies from 500 to 960 nm with increasing thickness (t) and agrees well with a scaling law of W proportional to root t. (C) 2012 The Japan Society of Applied Physics