Effect of Yttrium Addition on Structure and Magnetic Properties of Co<sub>60</sub>Fe<sub>20</sub>Y<sub>20</sub> Thin Films
Wen-Jen Liu,
Yung-Huang Chang,
Yuan-Tsung Chen,
Ding-Yang Tsai,
Pei-Xin Lu,
Shih-Hung Lin,
Te-Ho Wu,
Po-Wei Chi
Affiliations
Wen-Jen Liu
Department of Materials Science and Engineering, I-Shou University, Kaohsiung 840, Taiwan
Yung-Huang Chang
Bachelor Program in Interdisciplinary Studies, National Yunlin University of Science and Technology, 123 University Road, Section 3, Yunlin 64002, Taiwan
Yuan-Tsung Chen
Graduate School of Materials Science, National Yunlin University of Science and Technology, 123 University Road, Section 3, Yunlin 64002, Taiwan
Ding-Yang Tsai
Graduate School of Materials Science, National Yunlin University of Science and Technology, 123 University Road, Section 3, Yunlin 64002, Taiwan
Pei-Xin Lu
Graduate School of Materials Science, National Yunlin University of Science and Technology, 123 University Road, Section 3, Yunlin 64002, Taiwan
Shih-Hung Lin
Department of Electronic Engineering, National Yunlin University of Science and Technology, 123 University Road, Section 3, Yunlin 64002, Taiwan
Te-Ho Wu
Graduate School of Materials Science, National Yunlin University of Science and Technology, 123 University Road, Section 3, Yunlin 64002, Taiwan
Po-Wei Chi
Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
In this paper, a Co60Fe20Y20 film was sputtered onto Si (100) substrates with thicknesses ranging from 10 to 50 nm under four conditions to investigate the structure, magnetic properties, and surface energy. Under four conditions, the crystal structure of the CoFeY films was found to be amorphous by an X-ray diffraction analyzer (XRD), suggesting that yttrium (Y) added into CoFe films and can be refined in grain size and insufficient annealing temperatures do not induce enough thermal driving force to support grain growth. The saturation magnetization (MS) and low-frequency alternate-current magnetic susceptibility (χac) increased with the increase of the thicknesses and annealing temperatures, indicating the thickness effect and Y can be refined grain size and improved ferromagnetic spin exchange coupling. The highest Ms and χac values of the Co60Fe20Y20 films were 883 emu/cm3 and 0.26 when the annealed temperature was 300 °C and the thickness was 50 nm. The optimal resonance frequency (fres) was 50 Hz with the maximum χac value, indicating it could be used at a low frequency range. Moreover, the surface energy increased with the increase of the thickness and annealing temperature. The maximum surface energy of the annealed 300 °C film was 30.02 mJ/mm2 at 50 nm. Based on the magnetic and surface energy results, the optimal thickness was 50 nm annealed at 300 °C, which has the highest Ms, χac, and a strong adhesion, which can be as a free or pinned layer that could be combined with the magnetic tunneling layer and applied in magnetic fields.
