Preparation and Magnetoresistance Characteristics of Electrodeposited Ni‐Cu Alloys and Ni‐Cu/Cu Multilayers
Preparation and Magnetoresistance Characteristics of Electrodeposited Ni‐Cu Alloys and Ni‐Cu/Cu Multilayers
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DOI：
10.1149/1.1393900
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发表时间：
2000-09
影响因子：
3.9
通讯作者：
E. Toth-kadar;L. Péter;T. Becsei;J. Tóth;L. Pogány;T. Tarnóczi;P. Kamasa;I. Bakonyi;G. Láng-G.
中科院分区：
文献类型：
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作者：
E. Toth-kadar;L. Péter;T. Becsei;J. Tóth;L. Pogány;T. Tarnóczi;P. Kamasa;I. Bakonyi;G. Láng-G.
采用恒电流电沉积法，在硫酸盐/柠檬酸盐电解液中分别采用直流电镀和二次脉冲电镀的方法制备了Ni-Cu合金和Ni81Cu19/Cu多层膜。对于直流电镀Ni-Cu合金，建立了沉积速度和合金成分与沉积电流密度的函数关系，由此可以确定多层膜各组成亚层的合适沉积参数。通过测量在H=7KoE的磁场下的室温电阻率，发现Ni81Cu19多层膜存在各向异性磁阻(AMR)，而大多数Ni81Cu19/Cu多层膜既有巨磁电阻(GMR)，又有AMR贡献。最后，通过改变沉积脉冲的长度(开启时间)以及脉冲之间的恒定间隔(关闭时间)，也可以通过传统的脉冲电镀来制备镍铜合金。在这些脉冲镀镍铜合金中也出现了GMR贡献的明显证据，这可能是由于在阴极脉冲期间沉积的铁磁层之间形成了铜富集层。石英晶体微天平实验证实，在空闲时间内发生了交换反应。这些发现为研究双脉冲电镀多层膜的形成机理提供了有用的信息。
Galvanostatic electrodeposition was used to produce Ni-Cu alloys and Ni 81 Cu 19 /Cu multilayers by direct current (dc) plating and two-pulse plating, respectively, from a sulfate/citrate electrolyte. For the dc-plated Ni-Cu alloys, the deposition rate and the alloy composition were established as a function of the deposition current density, from which the appropriate deposition parameters for the constituent sublayers of the multilayers could be established. By measuring the resistivity at room temperature in magnetic fields up to H = 7 kOe, anisotropic magnetoresistance (AMR) was found for Ni 81 Cu 19 electrodeposits, whereas both giant magnetoresistance (GMR) and AMR contributions were observed for most Ni 81 Cu 19 /Cu multilayers. Finally, Ni-Cu alloys were also prepared by conventional pulse plating, varying the length of the deposition pulse (on-time) with constant separation (off-time) between the pulses. Clear evidence of a GMR contribution also appeared in these pulse plated Ni-Cu alloys which may be explained by the formation of a Cu enriched layer between the ferromagnetic layers deposited during the cathodic pulses. A quartz crystal microbalance experiment confirmed that an exchange reaction takes place during the off-time. These findings provide useful information on the formation mechanism of multilayers by the two-pulse plating technique.