Effect of the substrate temperature on the microstructure and magnetostrictive characteristics of the Tb 0.3Dy 0.7Fe 2 film

Abstract

The effect of the substrate temperature of the Tb 0.3Dy 0.7Fe 2 films formed by the flash evaporation process on the microstructure and magnetostrictive characteristics was examined. The microstructures and magnetic domains of the formed films were observed by transmission electron microscopy and the colloid Bitter method, respectively. Films formed at substrate temperatures below 405 K were found to be nanocrystalline structures with grains below 5 nm, for which very high magnetostrictive susceptibility could be observed. The films formed at temperatures between 410 K and 600 K were found to have grains of 5–10 nm. These grain sizes, magnetizations and magnetostrictions were almost constant, independent of temperature. At temperatures above 600 K, the grain size markedly increased up to 100 nm at 650 K, resulting in larger X-ray diffraction peaks and enlarged magnetic domains. Grown polycrystalline films, in which magnetizations seem to be initiated by the movement of magnetic domains, exhibited higher maximum magnetizations, however, lower magnetostrictive susceptibilities. Films formed in a contaminative condition yielded amorphous structures with very low magnetizations and magnetostrictions, independent of substrate temperatures below 650 K.