我们在真空离子束溅射设备中制备了Co-SiO2颗粒膜.其结构和磁性分别利用透射电子显微术(TEM)和铁磁共振(FMR)来研究.TEM分析表明Co纳米颗粒相互独立地分布在SiO2介质中,且尺寸分布非常窄.室温转角FMR实验显示薄膜具有单轴各向异性.变温FMR实验被用来研究在100～300K温度范围内的颗粒间相互作用强度随温度变化的关系(我们利用一理论模型计算了颗粒集合体中的铁磁部分所占比例和超顺磁部分所占比例).我们发现颗粒间相互作用强度除了与温度有关之外,还与Co颗粒的尺寸直接相关.
Co-SiO2 magnetic granular films were prepared with ion-sputtering method. Structures and magnetic properties of the films were studied by transmission electron microscopy (TEM) and ferromagnetic resonance (FMR) respectively. TEM analysis reveals that isolated Co nanoparticles disperse in the SiO2 matrix with very narrow size distributions. Angular variational FMR experiments indicate uniaxial anisotropies in the films. The temperature dependence of FMR data is employed to determine the degree of interparticle interactions in a temperature range of 100～300K, ferromagnetic fraction and superparamagnetic fraction are calculated. We find that the degree of interparticle interactions depends not only on the temperature, but also on the size of the Co nanoparticles.
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