Fe_xPt_(100-x)取向薄膜的结构与磁性

Structure and magnetic properties of Fe_xPt_(100-x) films

用电子束沉积法在加热到100℃的MgO(001)基板上生长了50nm厚的FexPt100-x取向薄膜,原子比成分范围为x=[10,85].在500℃进行保温2h的原位热处理后,分析样品的结构及沿面内和垂直于薄膜方向施加磁场的磁性行为.结果表明,随着x的增加,易磁化轴的方向在沿平行于膜面方向和垂直于膜面方向之间反复变化,取决于内秉的磁晶各向异性与外秉的形状各向异性之间的竞争.当x=60时,由于薄膜发生不完全的A1→L10相转变,形成了A1软磁相与L10硬磁相的复合体,样品沿平行和垂直于膜面方向磁化的矫顽力都达到5kOe(1Oe=79.5775Am-1)以上.沿膜面方向磁化时,矫顽力高于软磁相的磁晶各向异性场,并且正负向磁化的剩余磁化强度明显不相等.采用三磁畴软磁相模型,结合硬磁/软磁交换耦合作用,对此进行了解释.这种硬磁/软磁复合材料适合于用来制作磁力显微镜的各向同性高矫顽力探针.

FexPt100-x films（50 nm thick） with x = [10,85] in atomic percent were deposited by electron beam onto MgO（001） substrates heated to 100℃.And then the samples were annealed at 500℃ for 2 h.The crystalline structures and anisotropic magnetic properties were investigated.The direction of easy magnetization axis switches between horizontal direction and vertical direction with the increase of x,inducted by the intrinsic magnetocrystalline anisotropy and extrinsic shape anisotropy.At x = 60,a composite of disordered A1 phase and ordered L10 phase can be obtained due to the unfinished A1→L10 transformation.Both the horizontal coercivity and the vertical coercivity exceed 5 kOe.The horizontal coercivity is higher than the magnetocrystalline anisotropic field of soft A1 phase,and the horizontal coercive loop is asymmetric.The mechanism is discussed by a tri-domain model for the hard-soft exchange coupling system.This kind of hard/soft magnetic composite has the potential application to manufacture the cantilever for magnetic force microscope with high isotropic coercivity.