Mechanism of Quantum Transportation and Macroscopic Quantum Tunnel Effect in Nanomagnets

纳米磁体中的量子输运机制和宏观量子隧道效应

• 批准号: 11440116
• 负责人: MIYAJIMA Hideki
• 金额: $ 9.73万
• 依托单位: Keio University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11440116/
• 关键词: Nanomagnets; Quantum transportation; Spintronics; Tunnel effect; Quantum nanowire; Conductance quantization; Aharonov-Bohm effect; Domain-wall dynamics; 量子ナノワイヤー; AB効果; ナノリング; 弱局在; 磁性細線; ナノワイヤー

Diffusive as well as ballistic electronic transportation in nanomagnets has been investigated. The results are summed up as follows: (1) A conspicuous oscillation of magnetoresistance due to the Aharonov Bohm effect was found in a ferromagnetic NiFe nano-ring fabricated using the electron lithography. (2) The external magnetic and electric field dependence of the conductance quantization was found in Ni quantum wires. All the results indicate that the coherence of a conduction electron dominates the transport property in nanoscale ferromagnets in spite of the possible strong scattering of the conduction electron due to the local spins. Furthermore, the observed external-field dependence of the quantized conductance implies an important role of the magnetic structure in the ballistic transportation of electron in ferromagnets. On the other hand, correlations between the magnetic structures and the diffusive transportation, which has been theoretically predicted in ferromagnets, have not been observed so far in the present study. Some experiments for the investigation of the correlation using nanomagnets in which the magnetic structures can be controlled in terms of the magnetic shape anisotropy and the extra magnetic field are now under contemplation.

研究了纳米磁体中的扩散电子输运和弹道电子输运。主要研究结果如下：(1)在用电子光刻技术制备的NiFe铁磁纳米环中，由于Aharonov玻姆效应，出现了明显的磁阻振荡。(2)在Ni量子线中发现了外加磁场和电场对电导量子化的影响。所有结果表明，尽管传导电子可能由于局域自旋而发生强散射，但传导电子的相干性决定了纳米铁磁体的输运性质。此外，观测到的量子化电导的外场依赖关系表明，磁结构在铁磁体中电子的弹道输运中扮演着重要的角色。另一方面，到目前为止，还没有观察到铁磁体的磁结构和扩散输运之间的关联，这是理论上预测的。利用纳米磁铁研究这种关联的一些实验正在进行中，其中的磁结构可以通过磁形各向异性和外加磁场来控制。

项目成果

T.Ono, H.Miyajima et al.: "Magnetic and transport properties of magnetic wires down to 20mm in width"Journal of Magnetism and Magnetic Materials. 226-230. 1831-1832 (2001)

T.Ono、H.Miyajima 等人：“宽度达 20mm 的磁线的磁性和传输特性”《磁性与磁性材料杂志》。

H.Katsuno, H.Miyajima et al.: "Galvanomagnetic effect and domain wall resistance of ferromagnetic Fe-Ni wire in submicrometer width"Journal of Magnetism and Magnetic Materials. 226-230. 1864-1866 (2001)

H.Katsuno、H.Miyajima 等人：“亚微米宽度铁磁 Fe-Ni 线的电磁效应和畴壁电阻”《磁性与磁性材料杂志》。

檜上竜也,清水正義,小野輝男,宮島英紀: "強磁性体-超伝導体複合構造膜の磁化過程"日本応用磁気学会誌. 24巻,9号. 1258 (2000)

日野达也、清水正义、小野辉夫、宫岛秀树：“铁磁体-超导体复合结构薄膜的磁化过程”日本应用磁学学会杂志第 24 卷，第 9. 1258 期（2000 年）。

T.Ono, H.Miyajima., et al.: "Magnetic and transport properties of magnetic wires down to 20nm in width"Journal of Magnetism and Magnetic Materials. 226-230. 1831-1832 (2001)

T.Ono、H.Miyajima. 等人：“宽度达 20 nm 的磁线的磁性和传输特性”《磁性与磁性材料杂志》。

Y.Ooka, H.Miyajima., et al.: "Conductance quantization in ferromagnetic Ni nanowire"Journal of Magnetism and magnetic Materials. 226-230. 1848-1849 (2001)

Y.Ooka、H.Miyajima. 等人：“铁磁 Ni 纳米线中的电导量子化”《磁性与磁性材料杂志》。