在MgO(001)基板上生长连续的L10-FePt 纳米薄膜

用磁控溅射法在加热到400℃的MgO(001)基片上沉积了总厚度为25 nm 的Fe(0.6 nm)/Fe_30.5Pt_69.5(1.9nm)]₁₀ 多层连续薄膜, 并对其在500, 900]℃的温度范围进行了3h 的真空热处理. 结果表明, 薄膜在沉积过程中发生了层间扩散, 形成A1 相的FePt 合金, 表现为软磁特性; 热处理温度高于700℃时, 薄膜内形成L1₀ 相的(001)织构, 其单轴磁晶各向异性能高于2.5×10⁷ erg cc^-1; 薄膜能在800℃以下保持形貌连续. 借助于半导体载流子扩散和复合模型, 对薄膜在高温下形貌保持连续的机理进行了探讨. 分析认为, 虽然薄膜在沉积过程中发生了层间扩散, 但内部仍然残存微弱的周期性成分起伏, 这可以有效阻碍热处理过程中因相变而引起的Pt 元素析出, 从而抑制了因形成富Pt 晶界而导致的形貌不连续. 这种薄膜可以方便地用于微加工制作磁性阵列和隧道结.

Growth of continuous L1_0-FePt films on MgO(001) substrates

Fe(0.6 nm)/Fe_30.5Pt_69.5(1.9 nm)]₁₀ multilayer films with total thickness of 25 nm were deposited on MgO(001) substrates heated to 400°C by DC magnetron sputtering, and were subsequently subjected to a vacuum annealing for 3 h at temperatures in the range of 500, 900]°C. The as-deposited films had a soft magnetic A1 phase due to interlayer diffusion. Significant (001) texture of L10 phase was achieved by annealing the film at or over 700°C, with magnetocrystalline anisotropic energy exceeding 2.5×10⁷ erg cc^-1. The film morphology kept continuous till the annealing temperature was as high as 800°C. A modified diffusion-recombination model of carrier was adopted to discuss the morphology continuity of FePt film in high temperature environment. The slight compositional gradient in the film after interlayer diffusion might suppress the segregation of Pt and sufficiently prevented from the Pt enrichment which would result in the discontinuous boundaries. This kind of continuous L1₀ FePt film with preferential crystallographic orientation can be used conveniently for microfabrication of patterned arrays and magnetic tunnel junctions.