- 著者
- N. Watanabe S. Matsusawa Y. Miyato H. Itozaki
- 出版者
- (公社)日本磁気学会
- 雑誌
- Journal of the Magnetics Society of Japan (ISSN:18822924)
- 巻号頁・発行日
- vol.37, no.3-2, pp.235-238, 2013-05-01 (Released:2013-05-23)
- 参考文献数
- 7
- 被引用文献数
- 2 6
We measured the high-resolution magnetic images using an STM-SQUID microscope that combines a high-Tc superconducting quantum interference device (SQUID) with a scanning tunneling microscope (STM). In the STM-SQUID microscope, the STM probe plays the important role of a flux guide and is responsible for tunneling current detection. Therefore, it is essential to investigate the probe itself in order to improve the magnetic image resolution. We optimized the electrochemical polishing condition to realize the fine probe with a tip radius of 50 nm or less. We fabricated the various shaped probes by controlling the voltage during sharpening. The tip radius of 50 nm or less was achieved when the probe tip was sharpened at the applied voltage of 30 V. We then measured the magnetic images of typical magnetic materials, such as a steel sample and nickel thin films, using the probe with a tip radius of 50 nm or less. The magnetic domain structures were observed clearly.
- 著者
- N. Ota N. Gorjizadeh Y. Kawazoe
- 出版者
- (公社)日本磁気学会
- 雑誌
- Journal of the Magnetics Society of Japan (ISSN:18822924)
- 巻号頁・発行日
- vol.34, no.5, pp.573-578, 2010-09-01 (Released:2010-09-14)
- 参考文献数
- 31
- 被引用文献数
- 6 34
Several experiments have recently found room-temperature ferromagnetism in graphite-like carbon based materials. This paper offers a model explaining such ferromagnetism by using an asymmetric nano-graphene. Our first typical model is C48H24 graphene molecule, which has three dihydrogenated (-CH2) zigzag edges. There are several multiple spin states competing for stable minimum energy in the same atomic topology. Both molecular orbital and density function theory methods indicate that the quartet state (S=3/2) is more stable than that of doublet (S=1/2), which means that larger saturation magnetization will be achieved. We also enhanced this molecule to an infinite length ribbon having many (-CH2) edges. Similar results were obtained where the highest spin state was more stable than lower spin state. In contrast, a nitrogen substituted (-NH) molecule C45N3H21 demonstrated opposite results. that is, the lowest spin state (S=1/2) is more stable than that of highest one (S=3/2), which arises from the slight change in atom position.
- 著者
- R. Zhang T. Hamada S. Inagi Y. Kitamoto
- 出版者
- (公社)日本磁気学会
- 雑誌
- Journal of the Magnetics Society of Japan (ISSN:18822924)
- 巻号頁・発行日
- vol.37, no.3-2, pp.303-306, 2013-05-01 (Released:2013-05-23)
- 参考文献数
- 20
- 被引用文献数
- 3
Novel multifunctional superparamagnetic and optical nanohybrids are fabricated for biomedical applications. This architecture involves a silica core surrounded by a thin shell of FePt that is further covered with an outer shell of gold. Polyethyleneimine was utilized as a linker to bridge the FePt shell with the gold shell, which allowed 3-nm gold nanoparticle seeds to be loaded and a uniform gold shell to be formed. These gold and FePt doubly coated silica nanoparticles take advantage of the tunable resonance absorption in the visible and near-infrared (NIR) ranges and can be controlled by using an external magnetic field, which makes them very promising candidates for future biomedical applications.