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arXiv 1808.06198cond-mat.mtrl-sci
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Ni掺杂Co/Cu多层膜中自旋相关散射和磁邻近效应作为原子磁性探针的研究

Spin-dependent scattering and magnetic proximity effect in Ni-doped Co/Cu multilayers as a probe of atomic magnetism

Yu O Tykhonenko-Polishchuk, D M Polishchuk, T I Polek, D D Yaremkevych, A F Kravets, A I Tovstolytkin, A N Timoshevskii, V Korenivski

摘要:

我们研究了在Cu间隔层中不同Ni掺杂水平的巨磁阻Co/Cu-Ni多层膜的自旋输运和铁磁共振性质。我们提出了一个实验证据的磁性到抗磁性转变的原子磁矩的Ni在Cu基体的浓度低于15原子。%的Ni。随着浓度的增加,Ni原子变成自旋散射中心,这在实验上表现为多层膜的GMR的阶梯状变化。在具有梯度掺杂Cu间隔物的多层膜中观察到这种行为,其中仅内部区域掺杂有Ni。在均匀掺杂的间隔层中,GMR随着Ni含量的增加而单调减小,这表明Ni原子是磁性的,并且在整个掺杂剂浓度范围内充当自旋弛豫中心。我们解释了所观察到的巨磁阻行为的差异,由于在均匀的间隔,这是有效地抑制在梯度间隔的强磁邻近效应。所观察到的磁性相变是完全支持我们详细的从头计算,考虑到在系统中的结构弛豫以及潜在的Ni集群。控制特定掺杂剂的原子磁性的损失或增益可以是探测和控制用于基于自旋阀和自旋扭矩的应用的材料和器件中的自旋弛豫的工具。

英文摘要:

We investigate the spin transport and ferromagnetic resonance properties of giant magnetoresistive (GMR) Co/Cu-Ni multilayers with variable levels of Ni doping in the Cu spacer. We present an experimental evidence for a magnetic-to-diamagnetic transition in the atomic magnetic moment of Ni in the Cu matrix for concentrations below 15 at. % Ni. As its concentration is increased, Ni atoms turn into spin scattering centers, which is manifested experimentally as a step-like change in the GMR of the multilayers. This behavior is observed in multilayers with gradient-doped Cu spacers, where only the inner region was doped with Ni. In the uniformly doped spacers the GMR decreases monotonously with increasing Ni content, indicating that Ni atoms are magnetic and act as spin relaxation centers in the entire dopant-concentration range studied. We explain the difference in the observed GMR behavior as due to a strong magnetic proximity effect in the uniform spacers, which is efficiently suppressed in the gradient spacers. The observed magnetic phase transition is fully supported by our detailed ab-initio calculations, taking into consideration structural relaxation in the system as well as potential Ni clustering. Controlling the loss or gain of the atomic magnetism for a specific dopant can be a tool in probing and controlling spin relaxation in materials and devices for spin-valve and spin-torque based applications.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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