Co-Fe metal/native-oxide multilayers: a new direction in soft magnetic thin film design I. Quasi-static properties and dynamic response
Co-Fe metal/native-oxide multilayers: a new direction in soft magnetic thin film design I. Quasi-static properties and dynamic response
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DOI：
10.1109/tmag.2005.847631
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发表时间：
2005-06
影响因子：
2.1
通讯作者：
Geoffrey S. D. Beach;A. Berkowitz
中科院分区：
文献类型：
--
作者：
Geoffrey S. D. Beach;A. Berkowitz
磁记录向千兆赫兹数据速率的发展给软磁材料的设计带来了相当大的挑战。困难在于满足两组相互冲突的要求：1)同时获得软磁性能、高饱和磁化强度和高电阻率，后者需要限制涡流损耗，以及2)平衡带宽和磁导率之间的内在权衡，这两个参数分别与各向异性场的正相关和逆相关所施加的内在权衡。本文描述了一种满足这些要求的新型软磁复合系统：金属/自然氧化物多层(MNOM)薄膜，由超薄磁性自然氧化层隔开的纳米颗粒高磁矩Co/subx/Fe/sub100-x/层组成。高阻磁性氧化物层将金属层电隔离，同时将它们进行磁性耦合，并最大限度地减少传统金属/非磁性氧化物复合材料中存在的体积平均饱和磁化强度的下降。此外，MNOM复合材料的“交换平均”软磁性能包括理想的低色散面内单轴各向异性，其大小与合金中Co的分数x成线性关系。由此产生的各向异性控制，加上大的饱和磁化强度，允许在很大范围内调节磁导率和谐振频率，以满足特定的应用要求。
The progression toward gigahertz data rates in magnetic recording has introduced considerable challenges to soft magnetic materials design. The difficulties lie in satisfying two sets of conflicting demands: 1) simultaneously achieving soft magnetic properties, high saturation magnetization, and a high resistivity, with the latter required to limit eddy-current losses and 2) balancing the inherent tradeoff between bandwidth and permeability imposed by the direct and inverse dependences, respectively, of these two parameters on the anisotropy field. This paper describes a new soft magnetic composite system that meets these requirements: a metal/native-oxide multilayer (MNOM) film consisting of nanogranular high-moment Co/sub x/Fe/sub 100-x/ layers separated by ultrathin magnetic native oxide layers. The high-resistivity magnetic oxide layers isolate the metallic layers electrically, while coupling them magnetically and minimizing the decrease in volume-averaged saturation magnetization that exists in traditional metal/nonmagnetic oxide composites. In addition, the "exchange-averaged" soft magnetic properties of the MNOM composite include an ideal low-dispersion in-plane uniaxial anisotropy whose magnitude varies linearly with the fraction x of Co in the alloy. The resulting anisotropy control, together with the large saturation magnetization, permits the permeability and resonance frequency to be tuned over a wide range to meet specific application requirements.