Composition-dependent ratio of orbital-to-spin magnetic moment in structurally disorderedFexPt1−xnanoparticles
Composition-dependent ratio of orbital-to-spin magnetic moment in structurally disorderedFexPt1−xnanoparticles
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DOI：
10.1103/physrevb.69.054417
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发表时间：
2004-02
影响因子：
3.7
通讯作者：
M. Ulmeanu;C. Antoniak;U. Wiedwald;M. Farle;Z. Frait;Shouheng Sun
中科院分区：
文献类型：
--
作者：
M. Ulmeanu;C. Antoniak;U. Wiedwald;M. Farle;Z. Frait;Shouheng Sun
采用多频电子顺磁共振方法，在室温下测量了不同Fe浓度的3 nm FexPt 1 - x纳米颗粒的轨道磁矩与自旋磁矩之比μ efL/μ efS，并将其平均为Fe和Pt的元素贡献。通过详细的g因子分析，我们确定该比值从μ e f f L/μ e f f S=0.049（x=0.43）下降到μ e f f L/μ e f f S=0.016（x=0.70），这比体铁值（μ F e L/μ F e S=0.045）小得多。所观察到的浓度依赖性比Fe x Pt 1 - x散装样品计算的强得多，并揭示了纳米颗粒系统的受限电子结构的可能变化。μ efL/μ efS的比值在磁各向异性能为零的浓度（x =0.70）处取最低值。当x>0.72时，发生从fcc结构到Fe bcc结构的相变，导致体积比再次增加。
The ratio of orbital-to-spin magnetic moment μ e f f L/μ e f f S averaged over the element-specific contributions of Fe and Pt has been measured for 3-nm Fe x Pt 1 - x nanoparticles at room temperature using the multifrequency electron paramagnetic resonance method for different concentrations of Fe. From a detailed g-factor analysis we determine that the ratio decreases from μ e f f L/μ e f f S=0.049 for x=0.43 to μ e f f L/μ e f f S=0.016 for x=0.70 which is much smaller than the bulk iron value (μ F e L/μ F e S=0.045). The observed concentration dependence is much stronger than the one calculated for Fe x Pt 1 - x bulk samples and reveals likely changes of the confined electronic structure of the nanoparticle system. The ratio μ e f f L/μ e f f S takes the lowest value at the concentration (x =0.70) where the magnetic anisotropy energy vanishes in bulk alloys. For x>0.72 a phase transition from a fcc to the Fe bcc structure occurs resulting in the increased bulk ratio again.