Field-dependent thermal conductivity and Lorenz number in Co/Cu multilayers
Field-dependent thermal conductivity and Lorenz number in Co/Cu multilayers
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DOI：
10.1103/physrevb.87.134406
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发表时间：
2013-04
影响因子：
3.7
通讯作者：
J. Kimling;K. Nielsch;K. Rott;G. Reiss
中科院分区：
文献类型：
--
作者：
J. Kimling;K. Nielsch;K. Rott;G. Reiss
非弹性散射机制对巨磁电阻(GMR)效应的影响一直存在争议。例如，可以通过比较呈现巨磁电阻的磁性多层膜中的电荷电流和热流来解决这个问题。对这些实验的解释是基于维德曼-弗兰兹定律的。由于这一定律只适用于弹性散射，实验观察到的偏离这一定律的情况通常归因于非弹性散射的存在，反之亦然。我们开发了两个简单的模型来证明这种解释在GMR效应的背景下可能导致错误的结论。我们采用了一种基于所谓的3-确保数学方法的测量技术来研究Co/Cu多层膜的面内电导和热导率随温度范围内磁场的变化。我们的实验结果表明，Wiedemann-Franz定律在所研究的温度范围内是成立的。利用所建立的简单模型，我们得出结论：在Co/Cu多层膜中，电子-磁振子散射对GMR效应的影响可以忽略不计。我们进一步得出结论，电子-声子散射具有与Co/Cu多层膜中电子在界面处的主要弹性散射相同的自旋不对称性。
The influence of inelastic scattering mechanisms on the giant magnetoresistance (GMR) effect has been controversially discussed. This issue can be addressed, for example, by comparing charge currents with heat currents in magnetic multilayers that exhibit GMR. The interpretation of such experiments is based on the Wiedemann-Franz law. Due to the fact that this law only holds for elastic scattering, experimentally observed deviations from this law are usually attributed to the presence of inelastic scattering and vice versa. We develop two simple models to demonstrate that this interpretation can lead to wrong conclusions in the context of the GMR effect. We employ a measurement technique that is based on the so-called 3$\ensuremath{\omega}$ method to study the in-plane electrical and thermal conductivities of a Co/Cu multilayer in dependence on magnetic fields over a wide range of temperatures. Our experimental results indicate that the Wiedemann-Franz law holds over the temperature range investigated. Using the simple models developed, we conclude that the influence of electron-magnon scattering on the GMR effect in the Co/Cu multilayer is negligible. We further conclude that electron-phonon scattering is characterized by the same spin asymmetry as the predominant elastic scattering of electrons at interfaces in the Co/Cu multilayer.