铁离子注入外延钯薄膜的铁磁复合自排列
Ferromagnetic Composite Self-Arrangement in Iron-Implanted Epitaxial Palladium Thin Films
摘要:
我们报告的稀$Pd_{1-x}Fe_x$组合物的形成下的离子束注入外延钯薄膜的可调磁性能。通过将$40 keV$和$3.0\cdot10^{16}$离子分别注入到MgO(001)衬底上的钯膜中,获得了平均铁含量为$0.025$、$0.035$或$0.075$的$ions/cm^2$二元合金。结构和磁性研究表明,铁原子占据规则的fcc-晶格Pd-网站没有任何二次结晶相的形成。所有铁离子注入的Pd薄膜在低温下(低于$200 K$)都表现出铁磁性,居里温度和饱和磁化强度都由注入的铁离子剂量决定。与Fe含量相近的分子束外延生长的$Pd_{1-x}Fe_x$合金薄膜的磁性能相比,Fe离子注入的Pd薄膜具有较弱的面内磁晶各向异性,从而具有较低的矫顽力。在注入的$Pd_{1-x}Fe_x$膜中观察到的多个铁磁共振表明由于旋节分解成具有相同晶体对称性但不同铁含量的区域(推测为层)而形成磁不均匀状态。多相磁结构相对于在$770 K$的真空退火是稳健的,尽管朝向定义明确的局部$Pd-Fe$组合物发展。
英文摘要:
We report on the formation of the dilute $Pd_{1-x}Fe_x$ compositions with tunable magnetic properties under an ion-beam implantation of epitaxial Pd thin films. Binary $Pd_{1-x}Fe_x$ alloys with a mean iron content $x$ of $0.025$, $0.035$ or $0.075$ were obtained by the implantation of $40 keV$ $Fe^+$ ions into the palladium films on MgO (001) substrate to the doses of $0.5\cdot10^{16}, 1.0\cdot10^{16}$ and $3.0\cdot10^{16}$ $ions/cm^2$, respectively. Structural and magnetic studies have shown that iron atoms occupy regular fcc-lattice Pd-sites without the formation of any secondary crystallographic phase. All the iron implanted Pd films reveal ferromagnetism at low temperatures (below $200 K$) with both the Curie temperature and saturation magnetization determined by the implanted iron dose. In contrast to the magnetic properties of the molecular beam epitaxy grown $Pd_{1-x}Fe_x$ alloy films with the similar iron contents, the Fe-implanted Pd films possess weaker in-plane magnetocrystalline anisotropy, and, accordingly, a lower coercivity. The observed multiple ferromagnetic resonances in the implanted $Pd_{1-x}Fe_x$ films indicate a formation of a magnetically inhomogeneous state due to spinodal decomposition into regions, presumably layers, with identical crystal symmetry but different iron contents. The multiphase magnetic structure is robust with respect to the vacuum annealing at $770 K$, though develops towards well-defined local $Pd-Fe$ compositions.
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