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

通过将磁离子高剂量植入到绝缘氧化物中合成的金属 - 绝缘体纳米复合材料提供了有吸引力的结构，例如巨型磁性隧道连接。在植入100 keV fe^+离子的α-AL_2O_3单晶中观察到了显着的隧穿磁磁性（TMR）效应，其中植入的层暴露于约7-8％。获得的值大约是通过RF溅射制备的类似颗粒状Fe/al_2o_3膜观察到的大约的两倍。此外，我们通过顺序植入Fe和Co ions成功地合成了Al_2O_3材料中FECO合金的纳米化clus子。在FECO颗粒层中也证明了合金导致铁磁矩的增加。从结果中可以预期，在室温下，MR比率将增加到10％以上的值。通过这些研究，我们通过转化电子摩塞摩斯摩斯摩斯摩斯杆菌（CEMS）获得了有关植入的聚集状态的详细信息。 CEMS在原子尺度上提供了高度敏感和显微镜的平均值，以进行这种表征，尤其是当它与质量选择的 ^<57> Fe植入结合时。在研究中，我们报道了TMR效应的显着增强，通过改变植入Al_2o_3材料中的 ^<57> fe和 ^<59> cov的相对量，其能量为100 keV，并在Fe-，co-和feco Granular Films.fe-co-和feco granular fie的室温下呈现了最大的MR比率。在室温下进行，总剂量为1.5×10^<17>离子/cm^2，弹丸能量为74-105 keV。通过CEMS的测量和瞥见角X射线衍射（GXRD）的测量表明，将Fe植入SIO_2底物导致Si原子溶解到沉淀的铁纳米簇中。此外，据表明，将Cu离子添加到Fe/Al_2O_3和Fe/sio_2颗粒中促进了从超paragnetic到铁磁状态的过渡，这表明形成了亚稳态的Fe-Cu-Cu-Cu-Cu-Cu-Cu-Cu-Cu-Cu-Cu-Cu-Culoy Nano-Clusters。