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Study on the Origin of the Large Field Induced Magnetic Anisotropy of Nano-granular Soft Magnetic films and Its Applications

纳米颗粒软磁薄膜大场致磁各向异性的成因及其应用研究

基本信息

批准号：
13555099
负责人：
OHNUMA Shigehiro
金额：
$ 8.19万
依托单位：
The Research Institute for Electric and Magnetic Materials
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Soft magnetic metal-insulator nano-granular thin films such as (Fe, Co, Ni metals and their alloys)-(Al, Mg, RE oxides, nitrides and fluorides) are considered as the thin film-type high frequency magnetic inductive core materials, because of their high electrical resistivity (ρ), magnetic moments (Bs) and magnetic anisotropy field (Hk). We have found that the Co based films containing more than 10 at. % Pd exhibit huge Hk more than 200 Oe in keeping large ρ and Bs. The Hk is controllable in magnitude as well as in its uniaxial direction by adjusting of field-annealing conditions. A large Hk brings remarkable increase in the resonance frequency (fr) up to GHz region. In this project, we investigate the dependence of magnetic anisotropy (Ku) on field-annealing condition and composition for nano-granular soft magnetic films, and examine the origin of a large Ku of nano-granular Co-Pd based films from the structural experiments and discuss the applications of these films. Films were prepar … More ed by rf reactive magnetron sputtering with Ar+O_2 gases. Magnetic measurements were conducted on both a vibrating sample magnetometer and a torque magnetometer. The features of the Ku for metal-insulator type nano-granular soft magnetic films can be summarized into four things; 1) extraordinary large magnitude of Ku, as large as 1.5x 10^5 erg/cc is found in Co-Pd-Si-O films, 2) Ku of the films is attributed to a magnetically field induced anisotropy, 3) unique materials dependence of Ku is found as Co-Pd based>Co based>Fe based films, and 4) anomalous compositional dependence of Ku in (FeCo)-AI-O films cannot be explained in terms of the atom pair ordering. Structural investigations by HREM and SAXS have revealed a model to explain the Ku of Co-Pd-Si-O films. A large Ku of Co-Si-Pd-O films is attributed to a realignment of atoms at interfaces between granules and between granule and matrix, resulting in a strong anisotropy due to Co-Pd surrounded by a low symmetrical atomic environment. A crystal magnetic anisotropy of granule metals may also be related to the magnitude of Ku in the films. These soft magnetic thin films will be a strong candidate for magnetic core materials of inductor and transformer and so on at a few GHz range. And their large permeability near fr suggests that these films are a suitable for the electromagnetic noise suppression materials at GHz band. Less

软磁金属绝缘体纳米颗粒薄膜（Fe, Co， Ni金属及其合金）-（Al, Mg， RE氧化物，氮化物和氟化物）具有较高的电阻率（ρ），磁矩（Bs）和磁各向异性场（Hk），被认为是薄膜型高频磁感应磁芯材料。我们发现Co基薄膜含有超过10个at。% Pd在保持大的ρ和b时，表现出大于200oe的巨大Hk。通过调整现场退火条件，Hk在大小和单轴方向上都是可控的。较大的Hk使谐振频率（fr）在GHz区域内显著增加。在本项目中，我们研究了磁各向异性（Ku）对纳米颗粒软磁薄膜的场退火条件和组成的依赖性，并从结构实验中考察了大Ku的纳米颗粒Co-Pd基薄膜的来源，并讨论了这些薄膜的应用。采用射频反应磁控溅射技术，用Ar+O_2气体溅射制备了薄膜。对振动样品磁强计和转矩磁强计进行了磁测量。金属绝缘体型纳米颗粒软磁薄膜的Ku特性可以概括为四个方面；1)在Co- pd - si - o薄膜中发现了异常大的Ku，高达1.5x 10^5 erg/cc; 2)薄膜的Ku归因于磁场诱导的各向异性；3)在Co- pd基>Co基>Fe基薄膜中发现了独特的材料依赖性；4)(FeCo)-AI-O薄膜中Ku的异常成分依赖性不能用原子对排序来解释。HREM和SAXS的结构研究揭示了Co-Pd-Si-O薄膜的Ku的模型。Co-Si-Pd-O薄膜的高Ku值归因于颗粒之间和颗粒与基体之间的界面原子重新排列，由于Co-Pd被低对称的原子环境包围，导致其具有很强的各向异性。颗粒金属的晶体磁性各向异性也可能与薄膜中Ku的大小有关。这些软磁薄膜将在几GHz范围内成为电感、变压器等磁芯材料的有力候选材料。其在fr附近的大磁导率表明，这些薄膜适合作为GHz频段的电磁噪声抑制材料。少