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首页> 外文会议>NATO Advanced Study Institute on Magnetic Storage Systems Beyond 2000, Jun 25-Jul 7, 2000, Rhodes, Greece >GIANT MAGNETORESISTANCE OF Fe/Cr SUPERLATTICES IN WIDE FREQUENCY RANGE
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GIANT MAGNETORESISTANCE OF Fe/Cr SUPERLATTICES IN WIDE FREQUENCY RANGE

机译：Fe / Cr超晶格在大频率范围内的巨磁致电阻

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Until the present time only a limited number of investigations were devoted to studies of microwave electromagnetic properties of metallic magnetic multilayers. It was found that magnetic field dependence of microwave absorption in Fe/Cr/Fe epitaxial sandwiches was governed by giant magnetoresistive effect. The direct correlation between the giant magnetoresistive effect (GMR) and the transmission of electromagnetic waves through Fe/Cr superlattices was established. However, these experiments were performed in the 'current-in-plane' (CIP) geometry because the microwave eddy currents were in the plane of the layers. Ref. 3 represents preliminary experimental results on the microwave absorption of the metal superlattices in the 'current-perpendicular-to-plane' (CPP) geometry. Electromagnetic field penetration is one of the most suitable methods for the investigation of the high-frequency GMR effect. The penetration of the electromagnetic waves in a wide frequency range is investigated here in the Fe/Cr superlattices. There are three different frequency intervals of interest. In the first one, at the lowest frequencies, where 1/(σδZ)δ/L, the transmission coefficient is practically independent of magnetic field intensity. Here σ is an effective conductivity, δ the skin depth, L the total thickness of metal, Z the impedance of the outer space. In the second interval, at the higher frequencies where the inequality is valid Lδ, the transmission coefficient D is inversely proportional to the effective conductivity: D=2/(ZσL). In this frequency interval the relative deviation of the transmission coefficient in magnetic field tends to the relative magnetoresistance. At microwaves, the inequality L<δ is still valid. The relative dc magnetoresistance exactly equals to the relative deviation of the penetration amplitude. All these features are confirmed experimentally at the frequencies from 1 MHz to 10 GHz. The investigation of the GMR over the wide frequency range gives us the principal limits of memory storage systems performance. The most interesting results of CPP microwave experiments are reported here in detail. A new simple method of CPP-magnetoresistance measurement has been demonstrated. Fe/Cr superlattices with non-collinear magnetic ordering of Fe layers were chosen as the subjects of investigation.
机译：迄今为止，仅有限的研究致力于金属磁性多层的微波电磁特性的研究。发现Fe / Cr / Fe外延夹层中微波吸收的磁场依赖性受巨磁阻效应支配。建立了巨磁阻效应（GMR）与电磁波通过Fe / Cr超晶格的传输之间的直接关系。但是，这些实验是在“平面内电流”（CIP）几何形状中进行的，因为微波涡流在各层的平面中。参考图3表示在“电流垂直于平面”（CPP）几何形状中金属超晶格的微波吸收的初步实验结果。电磁场穿透是研究高频GMR效应的最合适方法之一。在Fe / Cr超晶格中研究了电磁波在较宽频率范围内的穿透情况。有三个不同的感兴趣频率间隔。在第一个中，在最低频率（1 /（σδZ）>>δ/ L）处，传输系数实际上与磁场强度无关。此处σ是有效电导率，δ是趋肤深度，L是金属的总厚度，Z是外部空间的阻抗。在第二个间隔中，在不等式有效L <<δ的较高频率下，传输系数D与有效电导率成反比：D = 2 /（ZσL）。在该频率间隔中，磁场中的传输系数的相对偏差趋向于相对磁阻。在微波下，不等式L <δ仍然有效。相对直流磁阻恰好等于穿透幅度的相对偏差。所有这些功能均在1 MHz至10 GHz的频率上进行了实验验证。在宽频率范围内对GMR的研究为我们提供了内存存储系统性能的主要限制。 CPP微波实验最有趣的结果在这里详细报道。已经证明了一种新的简单的CPP磁阻测量方法。选择具有非共线磁性层的Fe / Cr超晶格作为研究对象。

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