We have studied domain nucleation phenomena in a (111)-oriented garnet bubble film in the presence of in-plane fields. From visual observations we have found that as the in-plane field is lowered from saturation, a homogeneous stripe nucleation occurs at a critical easy axis bias field H∥n, leading to a ``mixed polarity state'' at remanence. For bias fields different from H∥n, inhomogeneous bubble nucleation occurs which is dependent on the defect distribution in the sample and which can give rise to a bubble lattice at remanence. The bias field H∥n depends on the azimuthal angle φ of the in-plane field in the sample plane; it has threefold (cos3φ) and onefold (cosφ) symmetry components which can be related to cubic and tilted uniaxial anisotropy, respectively. The tilt of the uniaxial anisotropy is found to be along the same direction as, but significantly larger than, the actual tilt of the crystallographic axis, perhaps indicating a large sensitivity of growth anisotropy to misalignment. An orthorhombic anisotropy component is observed in the in-plane nucleation field. These results are compared to the results of photometric measurements of the type previously proposed by Shumate, Smith, and Hagedorn, and by Krumme, Hansen, and Haberkamp. A phase theory, modified to include finite-thickness effects phenomenologically, is developed to determine the conditions for second-order (stripe) nucleation in the presence of cubic, tilted uniaxial, and orthorhombic anisotropy. Analytical expressions are found for H∥n which can be used to evaluate the anisotropies from the data. The results are consistent with independent measurements of these anisotropies on the same specimen.

Early stages in thin film metal-silicon and metal-SiO2 reactions under rapid thermal annealing conditions: The rapid thermal annealing/transmission electron microscopy technique

Phenomenological anisotropy constants have been measured in three garnet bubble films with their surface normal slightly misoriented from the crystallographic [I11] direction. A tilted magnetic easy axis is found from measurements of homogeneous nucleation and bubble collapse in the presence of in-plane fields. An in-plane anisotropy is also found whose axes do not in general lie either normal to or in the easy-axis tilt plane. These results are shown to be consistent with a phenomenological growth anisotropy model which includes the film plane misorientation.

Epitaxial films with a composition of EUo.s4Y2.41Pbo.o3Fe3.s4Gal.lS0I2 have been laser annealed in forming gas, nitrogen, air and oxygen. Annealed films were studied using bubble statics, ferromagnetic resonance and x-ray techniques. Changes in the annealing ambient resulted in variations in the maximum saturation magnetization (41rM,) achieved, and in the laser power thresholds for film cracking and melting. In comparison with other atmospheres, oxygen allowed the use of greater laser power without film damage and yielded the highest saturation magnetization. The increase in 41r M, (above the as-grown value) produced by annealing in oxygen was more than 30% larger than achieved in air and more than 50% larger than reached in forming gas or nitrogen. The influence of an ambient is interpreted in terms of its abbility to suppress the formation of oxygen vacancies during laser annealing.

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