Synthesis of iron based alloy nanoparticles by ion implantation and the magnetic properties.

离子注入铁基合金纳米粒子的合成及其磁性能

基本信息

批准号：
15510108
负责人：
HAYASHI Nobuyuki
金额：
$ 2.18万
依托单位：
Kurume Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Metal-insulator nanocomposite layers synthesized by high dose implantation of magnetic ions into insulating oxides provide attractive structures such as giant magnetic tunneling junctions. An eminent tunneling magnetoresistance (TMR) effect was observed in α-Al_2O_3 single crystals implanted with 100 keV Fe^+ ions, where the implanted layers exhibit a magnetoresitance (MR) ratio of about 7〜8%. The obtained value is about twice as large as that observed for similar granular Fe/Al_2O_3 films prepared by rf sputtering. Furthermore, we have succeeded in synthesizing nanosizedclusters of FeCo alloys in the Al_2O_3 matrices by sequential implantation of Fe and Co ions. It was also demonstrated in the FeCo granular layers that the alloying leads to an increase of the iron magnetic moment. From the result it is expected for the MR ratio to increase to a value of more than 10% at room temperature.Through these studies we have obtained detailed information on the aggregation states of implanted … More Fe ions by means of conversion electron Mossbauer spectroscopy (CEMS). CEMS provides highly sensitive and microscopic means in atomic scale for such characterization especially when it is combined with the mass-selected ^<57>Fe implantation. In the studies we have reported an eminent enhancement of TMR effect by changing the relative amount of ^<57>Fe and ^<59>Co ions implanted in Al_2O_3 matrices with an energy of 100 keV and presented the largest MR ratio at room temperature among the values reported in the Fe-, Co-, and FeCo granular films.Furthermore, the implantation of ^<57>Fe and ^<63>Cu ions was performed at room temperature up to a total dose of 1.5×10^<17> ions/cm^2 with projectiles energies of 74-105 keV. It is shown by the measurements of CEMS and glancing angle X-ray diffraction (GXRD) that Fe implantation into SiO_2 substrate results in the dissolution of Si atoms into the precipitated iron nano-clusters. Furthermore, it is shown that the addition of Cu ions into both Fe/Al_2O_3 and Fe/SiO_2 granules promotes the transition from superparamagnetic to ferromagnetic states, indicating the formation of metastable Fe-Cu alloy nanoclusters. Less

通过将磁性离子高剂量注入到绝缘氧化物中合成的金属-绝缘体纳米复合材料层提供了有吸引力的结构，例如巨大的磁隧道结，在注入 100 keV Fe^+ 离子的 α-Al_2O_3 单晶中观察到了显着的隧道磁阻（TMR）效应。，其中注入层表现出约 7~8% 的磁阻 (MR) 比率，所获得的值约为两倍。正如通过射频溅射制备的类似粒状 Fe/Al_2O_3 薄膜所观察到的那样，我们还通过顺序注入 Fe 和 Co 离子，成功地在 Al_2O_3 基体中合成了纳米级 FeCo 合金簇。从结果来看，合金化导致铁磁矩增加，预计 MR 比在室温下会增加到 10% 以上。通过这些研究，我们通过转换电子穆斯堡尔能谱 (CEMS) 获得了有关注入 Fe 离子聚集状态的详细信息，特别是与它结合使用时，可以在原子尺度上提供高度灵敏的微观手段。在研究中，我们报道了通过改变^<57>Fe和^<59>Co的相对量来显着增强TMR效应。离子以 100 keV 的能量注入 Al_2O_3 基体中，在 Fe-、Co- 和 FeCo 颗粒薄膜中报告的值中，室温下呈现出最大的 MR 比。此外，^<57>Fe 和^< 63>Cu离子在室温下进行，总剂量为1.5×10^<17>离子/cm^2，射弹能量为74-105 keV 通过 CEMS 和掠射角 X 射线衍射 (GXRD) 测量表明，Fe 注入 SiO_2 基底导致 Si 原子溶解到沉淀的铁纳米团簇中。将Cu离子添加到Fe/Al_2O_3和Fe/SiO_2颗粒中促进了从超顺磁态到铁磁态的转变，表明亚稳态 Fe-Cu 合金纳米团簇的形成。