Influence of underlayers on the soft properties of high magnetization FeCo films
Influence of underlayers on the soft properties of high magnetization FeCo films
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DOI：
10.1063/1.1557653
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发表时间：
2003-05-15
影响因子：
3.2
通讯作者：
Matsunuma, S
中科院分区：
文献类型：
--
作者：
Jung, HS;Doyle, WD;Matsunuma, S
在Cu、NiFe、Ru、Ta/Cu、Ta/NiFe或Cu/IrMn衬底上溅射Fe_（65）Co_（35）（=FeCo）薄膜，发现其矫顽力H-c显著降低。对于薄至2.5 nm的Cu、NiFe和Ru底层，观察到H-c从120 Oe降低到7-12 Oe，但对于Ta，则更少。Cu底层显著地将最大各向异性场从2 kOe减小到40 Oe，导致定义良好的面内平均单轴各向异性场H（k）类似于30 Oe。Cu的饱和磁致伸缩为（47+/-4 x10（-6），与Cu和FeCo厚度无关。面内拉伸膜应力随底层厚度t（UL）从2 GPa下降到0.2 GPa，但远不如H-c的下降快。所有底层在FeCo中诱导（110）织构，其在Ta中最强。横截面的透射电子显微镜显示出异常的长程相干性与低角度晶界的FeCo没有底层。清晰的柱状晶粒是可见的，所有底层的平均晶粒尺寸近似于50 nm，对于Cu、NiFe和Ru，Ta下降到9-10 nm。仅这一点就足以用霍夫曼的涟漪理论定量地解释H-c的减少。(C)2003年，美国物理学会。
A remarkable reduction in coercivity H-c was found in sputtered Fe65Co35(=FeCo) films on Cu, NiFe, Ru, Ta/Cu, Ta/NiFe, or Cu/IrMn underlayers. A decrease in H-c from 120 to 7-12 Oe was observed for Cu, NiFe, and Ru underlayers as thin as 2.5 nm but less for Ta. A Cu underlayer significantly reduced the maximum anisotropy fields from 2 kOe to 40 Oe, resulting in a well-defined in-plane average uniaxial anisotropy field H(k)similar to30 Oe. The saturation magnetostriction with Cu was (47+/-4)x10(-6), independent of Cu and FeCo thicknesses. In-plane tensile film stress decreased with underlayer thickness t(UL) from 2 to 0.2 GPa but much less rapidly than the reduction in H-c. All underlayers induced a (110) texture in FeCo, which was strongest with Ta. Transmission electron microscopy of cross-sections showed an unusually long range coherence with low angle grain boundaries in the FeCo without an underlayer. Clear columnar grains were visible with all underlayers with an average grain size of similar to50 nm with Ta dropping to 9-10 nm for Cu, NiFe, and Ru. This alone is sufficient to explain quantitatively the reduction in H-c using Hoffmann's ripple theory. (C) 2003 American Institute of Physics.