FePt and CoPt Magnetic Nanoparticles Film for Future High Density Data Storage Media
FePt and CoPt Magnetic Nanoparticles Film for Future High Density Data Storage Media
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DOI：
10.1002/chin.200552214
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发表时间：
2004-09
期刊：
影响因子：
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通讯作者：
Xiangcheng Sun;Yunhe Huang;D. Nikles
中科院分区：
文献类型：
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作者：
Xiangcheng Sun;Yunhe Huang;D. Nikles
磁性L10 FePt和CoPt纳米粒子的可控自组装最近引起了极大的兴趣，并可能作为未来的超高密度数据存储介质。本文综述了自组装FePtCu纳米颗粒薄膜的化学合成方法以及溅射法制备CoPt/C和FePt/C颗粒薄膜的研究进展。并对它们新颖的结构特征和独特的磁性进行了综述。首先，在油酸和油胺稳定剂的存在下，通过化学还原Pt和Cu试剂以及热分解五羰基铁，合成了不同组成的单分散FePtCu纳米粒子阵列。所制备的颗粒具有FCC结构，平均直径为3.5 nm，并且具有超顺磁性。该粒子在烃类溶剂中分散良好，可以自组装成具有多种紧密堆积排列的二维或三维粒子阵列。在高于550°C的温度下对自组装膜进行热处理，将颗粒从FCC转变为L10相，得到高达9 kOe的面内折射率。X射线衍射分析表明，退火后的FePtCu薄膜中有Cu残留。磁滞曲线可分解为硬分量（Hc > 5 kOe）和软分量（Hc <2kOe）。另一方面，通过在不同衬底温度下退火沉积在Si衬底上的CoPt/C和FePt/C多层前驱体，获得了嵌入非磁性C基体中的CoPt和FePt纳米颗粒。薄膜的磁性和结构特性进行了研究，相对于双层厚度，退火条件和温度。在高温下直接沉积得到了平均粒径从几纳米到20纳米的有序FePt纳米粒子。这些颗粒表现出更高的磁有序比通过多层前体制成的颗粒。当FePt与C的比例一定时，薄膜表现出很强的垂直各向异性。
Controlled self-assembly of magnetic L10 FePt and CoPt nanoparticles has stimulated great interest recently and may serve as future ultrahigh-density data storage media. This article reviews chemical synthesis of self-assembled FePtCu nanoparticles film and fabrication of CoPt/C and FePt/C granular thin films by sputtering. Their novel structural characterisation and unique magnetic properties are also reviewed. Firstly, monodispersed nanoparticle arrays of FePtCu with varying composition were synthesized by chemical reduction of Pt and Cu reagents and thermal decomposition of Fe pentacarbonyl in the presence of oleic acid and oleyl amine stabilizers. As prepared particles had FCC structure with an average diameter of 3.5 nm and were superparamagnetic. The particles were well dispersed in hydrocarbon solvents and could be self-assembled into two or three dimensions particles arrays with a variety of close-packing arrangements. Heat-treatment of the self-assembled films at temperatures above 550°C transformed the particles from the FCC to the L10 phase, giving in-plane coercivities as high as 9 kOe. X-ray diffraction revealed that the Cu remained in the annealed FePtCu films. The magnetic hysteresis curves could be decomposed into a hard component (Hc > 5 kOe) and a soft component (Hc < 2 kOe). On the other hand, CoPt and FePt nanoparticles embedded in non-magnetic C matrix have been obtained by annealing CoPt/C and FePt/C multilayer precursors deposited onto Si substrate at different substrate temperature. The magnetic and structural properties of the films were investigated with respect to bilayer thickness, annealing conditions and temperature. Ordered FePt nanoparticles with average particle size from a few nanometers to about 20 nm were obtained directly by depositing at high substrate temperature. These particles showed higher magnetic ordering than particles made via multilayer precursors. With a certain FePt to C ratio, films showed strong perpendicular anisotropy.