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中国物理学会期刊

薄膜异质结中磁性斯格明子的相关研究

CSTR: 32037.14.aps.67.20180549

Skyrmions in magnetic thin film heterostructures

CSTR: 32037.14.aps.67.20180549
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  • 磁性斯格明子由于具有拓扑保护、尺寸小、驱动电流密度低等优异的属性,有望作为未来超高密度磁存储和逻辑功能器件的信息载体.为了满足器件中信息写入和读取的基本要求,需要在室温下实现斯格明子的精确产生、操控和探测.该综述简要介绍最近我们针对上述问题取得的一系列研究进展,包括:1)证明可以通过控制磁性薄膜材料的垂直磁各向异性在室温下产生斯格明子,并进一步在基于反铁磁的薄膜异质结中发现了室温、零磁场下稳定存在的斯格明子;2)证明能够利用电流产生的自旋轨道力矩操控斯格明子,并进一步制备出一种基于斯格明子的原理型器件,实现了利用电学方式产生和操控数量可控的斯格明子.

     

    Magnetic skyrmion is expected to function as an ideal information carrier for ultra-high density magnetic storage and logic functional device in the future due to its superior properties, such as topological protection, small size, and low driving current density for motion. In order to meet the basic requirements for writing and reading information in devices, one needs to be able to accurately generate, manipulate, and probe skyrmion at room temperature. Given that the history and latest developments of the skyrmion research will be reviewed comprehensively in other articles, in order to avoid repetition, in this article we briefly review a series of recent research advances we have made in magnetic multilayer materials in recent years, and discuss the advantages of relevant device applications and problems that need to be solved. They are included in three aspects as follows. 1) The room temperature skyrmion was observed in a wedge film Ta (5 nm)/Co20Fe60B20 (CoFeB) (1 nm)/Ta (t)/MgO (2 nm)/Ta (2 nm) by a polar magneto-optical Kerr microscope. Results showed that skyrmion can be created at room temperature by controlling the perpendicular magnetic anisotropy of magnetic thin film. In the following, we designed a thin film heterojunction containing an antiferromagnetic layer IrMn. The introduction of antiferromagnetic material can produce an exchange bias field in the magnetic layer, which can play the same role as an external magnetic field, making it possible to realize zero-field skyrmion. In this study, we have successfully observed a stable skyrmion at room temperature and zero magnetic field. 2) The spin-orbit torque generated by the current proved to be able to be used to manipulate the created skyrmion. In the fourth part of this review, we discuss the dynamic process of skyrmion driven by spin-orbit torque in IrMn/CoFeB heterojunctions, and the chirality of skyrmion can be deduced by the direction of its longitudinal motion driven by an applied current. Finally, a principle device based on the skyrmion is further fabricated. In this device, a set of binary data was recorded in the track in the presence and absence of skyrmion. Generating and manipulating numbers of skyrmions were realized by using a series of pulse currents with different amplitudes and widths. The detection of a skyrmion can be achieved by using a magnetic tunnel junction at the right end of the device. 3) The advantages of skyrmion as a storage device and the problems that need to be solved for practical applications were discussed.

     

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