Thickness dependence of microwave magnetic properties in electrodeposited Fe–Co soft magnetic films with in-plane anisotropy

• Published in: Physica. B, Condensed matter Vol. 407; no. 3; pp. 555 - 559
• Main Authors: Yang, Xu, Wei, Jian-Qiang, Li, Xing-Hua, Gong, Lu-Qian, Wang, Tao, Li, Fa-Shen
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.02.2012; Elsevier
• Subjects: Anisotropy; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electrodeposition; Exact sciences and technology; Film thickness; Magnetic films; Magnetic permeability; Magnetic properties; Magnetic properties and materials; Magnetic properties of monolayers and thin films; Magnetic properties of surface, thin films and multilayers; Mathematical analysis; Microwave permeability; Microwaves; Physics; Ripples; Soft magnetic film; Surface roughness; Electrodeposition; Surface roughness; Film thickness; Microwave permeability; Soft magnetic film; Effective field approximation; Microwave radiation; Magnetic hysteresis; Soft magnetic materials; Magnetic thin films; Thickness; Frequency shift; Magnetic permeability; Magnetic anisotropy; Size effect; Curve fitting; Cobalt alloys; Iron base alloys; Landau Lifshitz equation; Transition element alloys
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2011.11.049

In this work, the thickness effect of Fe 52Co 48 soft magnetic films with in-plane anisotropy on static and microwave magnetic properties was investigated. The hysteresis loop results indicated that the static in-plane uniaxial anisotropy field increased from almost 0–60 Oe with increasing film thickness from 100 to 540 nm and well-defined in-plane uniaxial magnetic anisotropy can be obtained as the thickness reached 540 nm or larger. Based on Landau–Lifshitz–Gilbert (LLG) equation, the microwave complex permeability spectra were analyzed and well fitted. The LLG curve-fitting results indicated that the initial permeability increased from 106 to 142 and the resonant frequency was shifted from 4.95 to 4.29 GHz as the film thickness was varied from 540 to 1500 nm. Moreover, it was found that there was a discrepancy between the static and the dynamically determined anisotropy field, which can be explained by introducing an additional effective isotropic ripple field. The decreased ripple field was suggested to result in a significant decrease of damping coefficient from 0.109 to 0.038.