Journal of the Vacuum Society of Japan
Online ISSN : 1882-4749
Print ISSN : 1882-2398
ISSN-L : 1882-2398
57 巻, 10 号
選択された号の論文の7件中1~7を表示しています
小特集「磁気・スピンイメージングの最前線 (2)」
解説
  • 鈴木 基寛
    2014 年 57 巻 10 号 p. 363-370
    発行日: 2014年
    公開日: 2014/10/29
    ジャーナル フリー
      X-ray Fourier transform holography (FTH) is one of the promising techniques for imaging of magnetic nanostructures. Coherent X-rays are used to record an interference pattern (hologram) of the object and reference waves, and a real-space image can be reconstructed by a simple inverse Fourier transform to the measured hologram. Thus, the FTH allows lensless imaging in a nanometer resolution, comparable to X-ray wavelengths, in principle. Magnetic contrast can be obtained using circularly polarized X-rays, which interact with electron's magnetic moments to give measurable dichroic signals in absorption/scattering intensities. FTH has several advantages over other magnetic imaging techniques; in particular, in-situ observation in strong magnetic fields is feasible since it is a photon-based probe. This article describes the principle of FTH, benefits from the technique, and recent highlights including in-situ imaging of sudden formation of local magnetic domain clusters, the microscopic origin of the Barkhausen effect, in a perpendicular magnetic film.
  • 孝橋 照生
    2014 年 57 巻 10 号 p. 371-376
    発行日: 2014年
    公開日: 2014/10/29
    ジャーナル フリー
      Spin-Polarized Scanning Electron Microscopy (Spin SEM) is one way for observing magnetic domain structures taking advantage of the spin polarization of the secondary electrons emitted from a ferromagnetic sample. This principle brings us several excellent capabilities such as high-spatial resolution better than 10 nm, and analysis of magnetization direction in three dimensions. In this paper, the principle and the structure of the spin SEM is briefly introduced, and some examples of the spin SEM measurements are shown.
  • 糸﨑 秀夫, 宮戸 祐治
    2014 年 57 巻 10 号 p. 377-381
    発行日: 2014年
    公開日: 2014/10/29
    ジャーナル フリー
      A SQUID microscope is one of the magnetic imaging methods to achieve both the good spatial resolution and quantitativity for magnetic imaging. Since the conventional SQUID microscopes adopt the low Tc superconducting SQUIDs, it is difficult to measure the samples under room temperature. We have developed a SQUID microscope with a scanning tunneling microscope (STM-SQUID) using a probe with a sharp tip made of permalloy and a high Tc superconducting SQUID. The submicron magnetic domains of ferromagnetic thin films were clearly observed under room temperature and the air condition. The STM-SQUID has also achieved the imaging of surface morphology with nanometer scale and magnetic field with submicron scale simultaneously.
  • 越川 孝範, 鈴木 雅彦, 安江 常夫, E. Bauer, 中西 彊, 金 秀光, 竹田 美和
    2014 年 57 巻 10 号 p. 382-390
    発行日: 2014年
    公開日: 2014/10/29
    ジャーナル フリー
      Low energy electron microscopy (LEEM) and photo-emission electron microscopy (PEEM) have been widely considered as powerful methods of real time observation with versatile functionality and high lateral resolution required for the dynamic measurements of surfaces and interfaces. Spin-polarized LEEM (SPLEEM), which is mainly described in this article, has a spin-polarized electron gun (spin gun) and makes detailed magnetic domain observation possible. We developed the spin gun having very high brightness, high spin-polarization and long life time which enabled us to conduct the dynamic imaging of magnetic domains as well. We adopted several innovative ideas to develop the high performance spin gun, e.g., the backside illumination of laser beam to a photo-cathode for high brightness, strained super lattices of GaAs/GaAsP for high spin-polarization and extremely high vacuum for long life time of photo-cathodes. Such novel SPLEEM has been applied to [CoNix]y system, one of the promising multi-layered materials for spintronics devices.
  • 長尾 全寛, 肖 英紀, 木本 浩司
    2014 年 57 巻 10 号 p. 391-397
    発行日: 2014年
    公開日: 2014/10/29
    ジャーナル フリー
      Magnetic skyrmions, where the spin configuration is a vortexlike spin swirling, show intriguing phenomena such as the topological Hall effect, and motion under ultralow electric-current density, leading to new magnetic devices. In colossal magnetoresistive manganites, the possible presence of magnetic skyrmion-like structures has been discussed so far. Lorentz transmission electron microscopy (LTEM) has an advantage of being able to observe such local magnetization distributions in real space. We therefore used LTEM to directly observe magnetic clusters in manganites. In the LTEM images, possible magnetic skyrmion-like vortices are visualized and show the repeated reversal of magnetic chirality caused by thermal fluctuation. When two magnetic clusters locate near each other, the repeated magnetization reversal becomes fully synchronized. In addition, we developed the quantitative determination of the barrier energy for the magnetization reversal by LTEM only.
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