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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.

本研究是关于纳米结构磁体的自旋拓扑和量子磁学的研究。本文的研究结果总结如下：1)利用一种新的磁化壁共振谱，测得半圆形纳米线中磁壁的质量为6.6×10~(-23)kg，与1948年V.W.多林的预测值吻合较好。结果表明，磁化壁受低交流电流密度的驱动，可以忽略不计的小焦耳加热。2)用磁力显微镜和磁阻方法研究了坡莫合金丝蜂窝网络的磁结构和磁化过程。研究发现，这种磁结构受类似于冰规则的磁相互作用的支配。通过降低网络顶点处的交换能，冰规型的相互作用导致了磁化过程的转变。3)测量了三层Py/Cu/Py纳米结构的磁阻。4)研究了电导量子化条件下弹道纳米触头的磁阻效应和电流-电压特性。通过Py薄膜的铁磁共振，在室温下观察到了Py/Pt薄膜中自旋霍尔效应的反转过程。6)研究了射频范围内单根铁磁纳米线的电导，阐明了自旋扭矩二极管效应的磁场和频率关系。