Growth-induced magnetic anisotropy in seven different mixed rare-earth iron garnets

Abstract

We have measured the noncubic magnetic anisotropy in seven different compositions of rare‐earth iron garnets, using bulk single‐crystal samples grown from a flux. Several of these compositions supported magnetic bubble domains. The noncubic anisotropy is growth induced, and for each composition we investigated samples from both types of growth facets which occur in bulk garnet growth. Anisotropy energies as large as 7×10⁴ erg/cm³ were found, and three distinct anisotropy orientations were resolved. The results have been analyzed within the framework of a two‐parameter model for growth‐induced anisotropy, and we find general agreement although there are some discrepancies. For one composition, Y₂Gd₁Al_0.8Fe_4.2O₁₂, we have measured the dependence of the noncubic anisotropy on temperature over the range 4.2–300°K. Only part of the observed temperature dependence is in good agreement with a microscopic calculation done by Sturge. Finally, we report on the annealing characteristics of the noncubic anisotropy. Typically tens of hours near 1200°C are required to anneal it away.