David M. Heinz

A stress model for heteroepitaxial magnetic oxide films grown by chemical vapor deposition

Abstract A simple physical model is presented which predicts the sign and magnitude of stress in heteroepitaxial films. The model explains experimental observations of ferromagnetic resonance, domain structure, and crazing in magnetic oxide films grown by chemical vapor deposition (CVD) on non-magnetic substrates. It provides a means of predicting and developing compatible film-substrate combinations for epitaxial bubble domain materials utilizing a stress-induced uniaxial magnetic anisotropy. A basic result of the model, the conditions under which films can be grown in compression, has been verified experimentally for CVD iron garnets.

Mobile Cylindrical Magnetic Domains in Epitaxial Garnet Films

The properties of cylindrical domains in wafers of bulk single crystals of various magnetic oxides have been extensively studied and described in recent months. Mobile cylindrical domains have been produced in single‐crystal thin films of gallium‐substituted yttrium iron garnet. The deposits are formed by chemical vapor deposition onto nonmagnetic garnet substrates greater than 1 cm2 in area. A model of magnetic anisotropy in epitaxial films is proposed and shown to be in good agreement with experimental domain observations. In a typical sample, a domain diameter of 8 μ is observed in a 6‐μ‐thick film at a bias field of 25 Oe. From the domain translational velocity of 5600 cm/sec, a cylindrical domain mobility of 1500 cm/sec Oe has been calculated. A fractional change in cylindrical domain diameter of −0.07%/°K has been measured at 300°K. Annealing at 1570°K for several hours did not alter the Neel temperature or the optical transmission spectrum.