Thickness-dependent magnetic anisotropy in obliquely deposited Fe(001)/Pd thin film bilayers probed by VNA-FMR

• 来源期刊: 中国物理B（英文版）
• 关键词: oblique angle deposition iron film thickness magnetic anisotropy ferromagnetic resonance
• 年，卷（期）: 2019,（7）
• 页码范围: 522-528
• 页数: 7页
• 语种: 英文
• DOI: 10.1088/1674-1056/28/7/077502

摘要

The thickness-dependent magnetic anisotropy of obliquely deposited Fe(001)/Pd thin films on Mg(001) is investi-gated by fitting the field-dependent resonant field curve using the Kittel equation. In this study, three Fe film samples with thicknesses of 50 monolayers (ML), 45 ML, and 32 ML deposited at 0°, 45°, and 55°, respectively, are used. The magnetic anisotropy constant obtained from ferromagnetic resonance (FMR) spectra exhibits a dominant fourfold magne-tocrystalline anisotropy (MCA) at the normal deposition angle with larger Fe thickness. However, the in-plane uniaxial magnetic anisotropy (UMA) is induced by a higher oblique deposition angle and a smaller thickness. Its hard axis lies be-tween the [100] and [010] directions. The FMR data-fitting analysis yields a precise measurement of smaller contributions to the magnetic anisotropy, such as in-plane UMA. Due to MCA, when the magnetic field is weaker than the saturated field, the magnetization direction does not always align with the external field. The squared frequency-dependent resonant field measurement gives an isotropic Landé g-factor of 2.07. Our results are consistent with previous experiments conducted on the magneto-optical Kerr effect (MOKE) and anisotropic magnetoresistance (AMR) systems. Thus, a vector network analyzer ferromagnetic resonance (VNA-FMR) test-method for finding UMA in obliquely deposited Fe(001)/Pd bilayer ferromagnetic thin films, and determining the magnetic anisotropy constants with respect to the film normal deposition, is proposed.