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Spin-Topology and Quantum Magnetics in Nano-Structured Magnetic Materials

纳米结构磁性材料中的自旋拓扑和量子磁学

基本信息

批准号：
16204027
负责人：
MIYAJIMA Hideki
金额：
$ 28.79万
依托单位：
Keio University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

This study is on the spin-topology and quantum magnetics in nano-structured magnets. The results of the present study are summarized as follows ;1)By using a new domain wall resonance spectroscopy, the mass of a magnetic wall in a semi-circle nano-line is determined to be 6.6x10-23 kg, the value of which is well in agreement with that predicted by V. W. Doring in 1948. It is shown that the domain wall is driven by low AC current density which enables negligible small Joule heating.2)The magnetic structure and magnetization process in a Permalloy wire-based honeycomb network have been investigated by means of MFM and magnetoresistance. It is found that the magnetic structure is governed by magnetic interaction similar to the ice rule. By decreasing the exchange energy at the vertices of the network, the ice-rule type of interaction causes a transition of the magnetization process.3)Magnetoresistance for tri-layered Py/Cu/Py nanoring is measured. The ring detects the electron coherence modulated by the inhomogeneous magnetization distribution.4)The magnetoresistance effect and the current-voltage characteristics in ballistic nano-contacts in the regime of conductance quantization are investigated. The spin arrangement in the contacts plays an important role for quantum conductance.5)The inverse process of the spin-Hall effect is observed at room temperature in a Py/Pt thin film by the ferromagnetic resonance of Py film.6)The conduction of a single ferromagnetic nanowire in a radio frequency range is investigated and the magnetic field and frequency dependences of the spin torque diode effect are clarified.

本论文主要研究纳米结构磁体中的自旋拓扑和量子磁学。主要结果如下：1）利用一种新的畴壁共振谱方法，测得半圆形纳米线中磁壁的质量为6.6 × 10 ~（-23）kg，与V.W. 1948年的杜林。结果表明，磁畴壁由低电流密度驱动，其焦耳热可忽略不计。2）采用磁流体力学和磁电阻方法研究了坡莫合金丝基蜂窝网络的磁结构和磁化过程。研究发现，磁结构是由磁相互作用类似的冰规则。通过降低网络顶点处的交换能，冰规则型相互作用引起磁化过程的转变。3）测量了三层Py/Cu/Py纳米环的磁电阻。环探测到了受非均匀磁化分布调制的电子相干性。4）研究了电导量子化下弹道纳米接触的磁电阻效应和电流-电压特性。在室温下，利用Py薄膜的铁磁共振现象，观察到Py/Pt薄膜中自旋霍尔效应的逆过程。6）研究了单根铁磁纳米线在射频范围内的导电行为，阐明了自旋矩二极管效应的磁场和频率依赖性。