Study of Metallic Multilayers Consisting of Magnetic and Superconducting Components

本研究的主题是研究人工结构超晶格中的磁性和超导行为，并发现由于它们的相互作用而产生的任何新现象。为此，已经进行了一个实验装置，通过使用氧化室连接到真空沉积系统，在那里通过在原子尺度上控制厚度来制备金属氧化物层的氧化物薄膜。磁性/磁性多层膜的研究取得了显著进展，并对人工制备的铁磁单层膜体系进行了研究。近年来，人们发现层间耦合是一个有趣的课题。在70 A左右，Fe层间通过Au层的相互作用改变了磁电阻的符号.在具有反平行磁结构的多层膜中，如Fe/Cr和Cu/Co/Cu/Ni（Fe），发现了一种新型的磁电阻.在前一种情况下，通过层间反铁磁耦合实现了反平行结构，并通过中子衍射直接证实了反平行磁结构。在后一种情况下，矫顽场的差异是反平行自旋结构的原因，因此，MR变化可以由非常小的字段引起。这种大的磁电阻效应被认为是人造金属多层膜的特征，垂直于多层膜方向的输运现象是非常有吸引力的问题。通过使用氧化室制备用于隧穿测量的样品。

The subject of this research is to study the magnetic and superconducting behaviors in artificially structured superlattices and to discover any new phenomenon as a result of their interplay. For this purpose, an experimental setup has been performed to prepare ultrathin oxide films by using the oxidation chamber connected to the ultrahigh vacuum deposition system, where ultrathin metal layers are prepared by controlling the thickness on an atomic scale. For the magnetization measurements, a sample-vibrating magnetometer was equipped.A remarkable advance was achieved in the study of magnetic/nonmagnetic multilayers and artificially prepared ferromagnetic monolayer systems have been investigated. It has been recently found that the interlayer coupling is an interesting subject. The interaction between Fe layers through Au layer was found to change the sign at about 70 A.A new type magnetoresistance was found in multilayers with antiparallel magnetic structure, such as Fe/Cr and Cu/Co/Cu/Ni (Fe). An antiparallel structure is realized by an interlayer antiferromagnetic coupling in the former case, and the antiparallel magnetic structure has been directly confirmed by neutron diffraction. In the latter case, the difference of coercive fields is the cause of antiparallel spin structure and therefore the MR change can be induced by very small fields. Such large MR effects are regarded to be characteristic of artificial metallic multilayers.Transport phenomena in the direction perpendicular to the multilayered films are very attractive problems. Samples for the tunneling measurements are prepared by using the oxidation chamber.