Electronic properties of 4-nm FePt particles -: art. no. 014422
Electronic properties of 4-nm FePt particles -: art. no. 014422
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DOI：
10.1103/physrevb.67.014422
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发表时间：
2003-01-01
影响因子：
3.7
通讯作者：
Gleiter, H
中科院分区：
文献类型：
--
作者：
Stahl, B;Ellrich, J;Gleiter, H
采用x射线衍射（XRD）、卢瑟福后向散射光谱（RBS）、透射电镜（TEM）、x射线光电子能谱（XPS）、磁强计和穆斯堡尔能谱（Mossbauer spectroscopy）研究了4 nm FePt金属颗粒的结构、电子和磁性能。在低温下，与FePt多层或大块样品相比，穆斯堡尔数据显示出异常高且定义明确的超细磁场。在油酸分子层中嵌入的FePt粒子的磁各向异性是由表面贡献引起的。在粒子矩和体积恒定的约束下，各向异性的分布在4.3 K时作为外场的函数反映在磁滞回线中。由于在高分辨率TEM图像中看到的面状，磁化反转不遵循简单的斯通-沃尔法斯开关。退火实验表明，在4nm尺寸下，只要防止团聚和颗粒生长，高温催化裂化相至少在560°c内是稳定的。
The structural, electronic and magnetic properties of 4 nm metallic FePt particles were studied by X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), transmission electron microscopy (TEM), X-ray photo electron spectroscopy (XPS), magnetometry and Mossbauer spectroscopy. At low temperatures, the Mossbauer data reveal an unusually high and well defined magnetic hyperfine field compared to FePt multilayer or bulk samples. The magnetic anisotropy of the as-prepared FePt particles embedded in a layer of oleic acid molecules arises from surface contributions. The distribution of anisotropy under the constraint of a constant particle moment and volume is reflected in the hysteresis loop as a function of external field at 4.3 K. Due to faceting as seen in the high resolution TEM images, the magnetization reversal does not follow the simple Stoner-Wohlfarth switching. The annealing experiments show that at a size of 4 nm the high-temperature fcc phase is stable up to at least 560degreesC as long as agglomeration and particle growth is prevented.