Fe_(21)Ni_(79)合金纳米线阵列的制备与磁性

Preparation and magnetic properties of Fe_(21)Ni_(79) alloy nanowire arrays

用交流电化学沉积方法,在多孔铝阳极氧化膜的柱形孔内制备直径约60nm,长度约为9·7μm的Fe21Ni79合金纳米线.采用扫描电镜、透射电镜、X射线衍射仪和振动样品磁强计对纳米线的形貌、结构和磁学性质进行了测试.结果表明,Fe21Ni79纳米线排列有序,长径比可控,合金呈fcc结构.当将其在外磁场下进行垂直磁化时,磁滞回线出现较高的矩形比0·86,矫顽力达1203Oe.且随着退火温度升高,矫顽力迅速增大,500℃时达到最大值1315Oe,之后又随退火温度的升高而下降.矩形比也呈现类似的变化规律.

By using AC electrochemical deposition, ordered Fe21 Ni79 alloy nanowire arrays were fabricated into the anodic alumina oxide （AAO） templates. The nanowires were about 60 nm in diameter and 9.7 μm in length. The morphology, structure and magnetic properties of the Fe21 Ni79 alloy nanowires were characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD） and vibrating sample magnetometer （VSM）, respectively. The results indicated that the nanowires in an array were very regular, with a controllable aspect ratio. Such nanowire arrays were in fcc structure. The hysteresis loops showed that the nanowire arrays had excellent perpendicular magnetic anisotropy with their easy magnetization axis parallel to nanowire arrays. The as-deposited samples had high squareness （Mr/Ms）（about 0.86） and large coercivity （as high as 1203Oe） when the external magnetic field was perpendicular to membranes. Annealing could improve the coercivity and squareness of nanowire arrays. Coercivity increased with temperature and reached its maximum value （1315Oe） at 500℃, then with further increasing temperature coercivity decreased sharply. The change of squareness followed a similar pattern.