CoPt(FePt)-C纳米复合膜的结构与磁性

Structure and magnetic properties of CoPt(FePt)-C nanocomposite films

用磁过滤脉冲真空电弧沉积方法制备了CoPt(FePt) C纳米复合薄膜 ,并在不同温度下进行了退火处理 ,研究了薄膜中碳的含量以及退火温度对薄膜结构与磁性能的影响 .制备态薄膜经过足够高的温度退火后 ,x射线衍射和磁力显微镜分析发现 ,在碳基质中生成了面心四方相的CoPt(FePt)纳米颗粒 .对于特定组分为Co2 4 Pt31 C4 5和Fe4 3Pt35C2 2的薄膜 ,矫顽力以及颗粒尺寸都随退火温度的升高而增大 ,当退火温度为 70 0℃时 ,Co2 4 Pt31 C4 5薄膜的矫顽力为 2 1× 10 5A m ,晶粒尺寸为 17nm ;当退火温度为 6 5 0℃时 ,Fe4 3Pt35C2 2 相应值分别为 2 8× 10 5A m和 10 5nm .

CoPt(FePt)-C nanocomposite thin films were prepared by a pulsed filtered vacuum arc deposition technique. Thermal annealing was performed in vacuum at various temperatures. The dependence of the magnetic properties on the carbon fraction and annealing temperature was studied. Both x-ray diffraction and magnetic force microscopy analyses confirmed the formation of nano-crystallites of face-centered-tetragonal phase of CoPt or FePt in the carbon matrix after annealing at a sufficiently high temperature. For the film with particular compositions of Co-24 Pt-31 C-45 and Fe-43 Pt-35 C-22, the coercivity and the grain size were observed to increase with increasing annealing temperature. For the Co-24 Pt-31 C-45 film at an annealing temperature of 700 degrees C, the coercivity was 2.1 x 10(5) A/m and the grain size was about 17nm. For the Fe-43 Pt-35 C-22 film at an annealing temperature of 650 degrees C the values were 2.8 x 10(5) A/m and 10.5nm, respectively.