MAGNETIC ANISOTROPIES OF SPUTTERED FE FILMS ON MGO SUBSTRATES
MAGNETIC ANISOTROPIES OF SPUTTERED FE FILMS ON MGO SUBSTRATES
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DOI：
10.1103/physrevb.52.13450
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发表时间：
1995-11-01
影响因子：
3.7
通讯作者：
ZABEL, H
中科院分区：
文献类型：
--
作者：
GORYUNOV, YV;GARIFYANOV, NN;ZABEL, H
铁磁共振（FMR）和超导量子干涉装置（SQUID）测量已被用来研究MgO（001）基底上射频溅射Fe薄膜的磁性。对于厚度 L 在 25-500 埃范围内的薄膜，在宽温度范围（20-400 K）下测量了 FMR 谱参数对薄膜平面中去磁场转动方向的依赖性。对共振场 H-0 的角度依赖性的分析使我们能够确定四倍立方各向异性常数 K-1 和有效磁化值 M(eff)。结果发现，两个值都随着 L 的减小而减小，并在低于一定厚度时接近恒定值。概述了 FMR 理论，表明对于去磁场位于薄膜平面的情况，各向异性常数可以解释为体积各向异性贡献和表面各向异性的 1/L 相关贡献（直至厚度 L 大于或等于 10(3) 埃）的组合。这意味着对于实验研究的厚度范围，薄膜可以被视为相对于表面扰动的“动态薄膜”。那么，K-1 值的特殊厚度依赖性可以解释为假设由于 K-1 和基底之间的不匹配而导致的应变弛豫延伸到距薄膜-基底界面最远 45 埃的距离。由于我们的 SQUID 测量表明饱和矩不依赖于厚度，因此可以得出结论，有效磁化强度 M(eff) 的厚度依赖性是由二阶单轴各向异性引起的，该二阶单轴各向异性主要源于界面位错表面和边缘附近晶体场的对称性破缺。
Ferromagnetic resonance (FMR) and superconducting quantum interference device (SQUID) measurements have been used to study the magnetic properties of rf sputtered Fe films on MgO(001) substrates. The dependences of the FMR spectra parameters on the direction of the de magnetic field turning in the plane of the films were measured in a wide temperature range (20-400 K) for films with thickness L in the range 25-500 Angstrom. The analysis of the angular dependence of the resonance field H-0 allowed us to determine the fourfold cubic anisotropy constant K-1 and the effective magnetization value M(eff). It was found that both values decrease with decreasing L and approach a constant value below a certain thickness. A theory of FMR is outlined demonstrating that for the case of the de magnetic field lying in a film plane, the anisotropy constant can be interpreted as a combination of a volume anisotropy contribution and a 1/L-dependent contribution from the surface anisotropy up to the thickness L greater than or equal to 10(3) Angstrom. This means that for the experimentally studied thickness range the films may be considered as ''dynamically thin films'' with respect to surface perturbations. Then the peculiar thickness dependence of the K-1 value can be explained assuming that the relaxation of the strain due to the mismatch between him and substrate extends to distances as far as 45 Angstrom from the film-substrate interface. Since our SQUID measurements show that the saturation moment does not depend on the thickness, it is concluded that the thickness dependence of the effective magnetization M(eff) is caused by a second-order uniaxial anisotropy arising mainly from the broken symmetry of the crystal field at surfaces and near the edges of interfacial dislocations.