Manifestation of Initial Crystallization and c-Axis Texture in Pr-Fe-B Magnetic Thin Films Grown on Glass Substrates under Volume Effect

Abstract

VSM, XRD, SEM, TEM, and EDS measurements were applied to investigate the relationship between the thickness and the structure of Pr-Fe-B layer which initiated and propagated crystallization of the Pr2Fe14B phase at 600 °C on the glass substrate. The magnetic properties of the sputtered Pr-Fe-B film were also investigated in terms of evolution of the Pr2Fe14B hard magnetic phase. The crystallization process was investigated for a range of the thickness of Pr-Fe-B layer from 25 to 125 nm. The thin film structure at the 50 nm thickness showed the initial crystalline characteristics of hard magnetic Pr2Fe14B phase, the fine signal of c-axis orientation, perpendicular magnetic anisotropy (PMA), and coercivity (Hc). SEM and TEM results revealed the blossom of surface morphology and the ordered layer structure of thin films, respectively. EDS result showed various concentration of the main magnetic elements occurred at the initial stage of crystallization. The growth of the Pr2Fe14B phase was supported by a new Fe3Si underlayer. The thin film containing non-uniform crystal grains and two-phase microstructure showed the coupling exchange appeared between the hard magnetic and soft magnetic phases. The magnetization properties (Hc, PMA) was strongly affected by the Si3N4 underlayer and glass substrate. Magnetic analysis suggests that a high-efficiency Pr-Fe-B thin film is made of a fine microstructure.