The development of magnetic materials with large uniaxial magnetic anisotropy (K u) and high saturation magnetization has attracted much attention in various areas such as high-density magnetic storage, spintronic devices, and permanent magnets. Although FeCo alloys with the body-centred cubic structure exhibit the highest M s among all transition metal alloys, their low K u and coercivity (H c) make them unsuitable for these applications. However, recent first-principles calculations have predicted large K u for the FeCo films with the body-centred tetragonal structure. In this work, we experimentally investigated the hard magnetic properties and magnetic domain structures of nanopatterned FeCo alloy thin films. As a result, a relatively large value of the perpendicular uniaxial magnetic anisotropy K u = 2.1 × 106 J·m−3 was obtained, while the H c of the nanopatterned FeCo layers increased with decreasing dot pattern size. The maximum H c measured in this study was 4.8 × 105 A·m−1, and the corresponding value of μ 0 H c was 0.60 T, where μ 0 represented the vacuum permeability.
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机译：具有大的单轴磁各向异性（K u）和高饱和磁化强度的磁性材料的开发在诸如高密度磁存储，自旋电子器件和永磁体等各个领域引起了很多关注。尽管具有体心立方结构的FeCo合金在所有过渡金属合金中均显示出最高的M s，但其低的K u和矫顽力（H c）使其不适用于这些应用。然而，最近的第一性原理计算已经预测了具有以身体为中心的四方结构的FeCo膜的大K u。在这项工作中，我们实验研究了纳米图案化FeCo合金薄膜的硬磁性能和磁畴结构。结果，获得了较大的垂直单轴磁各向异性K u = 2.1×10 6 J·m -3 的值，而纳米图案的H c FeCo层随着点图案尺寸的减小而增加。本研究测量的最大H c为4.8×10 5 A·m -1 ，μ0 H c的对应值为0.60 T，其中μ0表示真空渗透率。
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