Fabrication of magnetic nanoparticle-array recording media and their evaluation with probe heads

磁性纳米颗粒阵列记录介质的制备及其探针头的评估

• 批准号: 14350180
• 负责人: KITAMOTO Yoshitaka
• 金额: $ 10.88万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14350180/
• 关键词: Magnetic recording medium; Magnetic nanoparticle; Self-assembly; Nanoparticle array; Magnetic anisotropy; Ordered alloy; Fe-Pt; ナノ粒子; ラングミュア・プロジェット法; ラングミュア・ブロジェット法; FePt; 磁気緩和; LB法

The purpose of the present study is to establish fabrication techniques of Fe-Pt nanoparticle-array magnetic recording media and to evaluate their potential to achieve areal recording density over 1 tera-bit per square inch. The results are shown in the followings.1) We studied the relationship between chemical ordering and magnetic anisotropy for powder samples of Fe-Pt nanoparticles, and found that a volume ratio Q of ordered alloy phase evaluated with Mossbauer spectroscopy was a useful parameter to evaluate the chemical ordering. Whereas Q is a parameter for short-range ordering, S obtained from X-ray diffractometry is a parameter for long-range ordering. Magnetic anisotropy was evaluated with the maximum magnetic field of 90 kOe. Distribution of magnetic anisotropy-field H_k for partially ordered Fe-Pt nanoparticles was much broader than that for almost fully ordered Fe-Pt nanoparticles, and the low H_k components were included with a high volume ratio.2) Partially ordered Fe-Pt n … More anoparticles were successfully obtained with polyol reduction method of Fe and Pt salts by using microwave irradiation without any post-synthesis heat-treatment. The Fe-Pt nanoparticles synthesized at 250℃ with microwave irradiation exhibited volume ratio for ordered alloy phase of 60% and magnetic anisotropy field over 80 kOe.3) Mixing saturated fatty acid (C_nH_<2n> O_2) molecules to an Fe-Pt nanoparticle suspension assisted the formation of a nanoparticle monolayer on pure water surface without coagulation. Because the surface of the Fe-Pt nanoparticles is hydrophobic, interface energy with water surface is high. The fatty acid molecules probably reduced the interface energy as a buffer layer between the Fe-Pt nanoparticle-monolayer and water surface. Fatty acid molecules with n 【greater than or equal】 14 were effective for the formation, and the best one in view of the formation of regular nanoparticle-array was the molecule with n = 14.4) Carbon overcoats deposited with sputtering on Fe-Pt nanoparticle assembly-films successfully prevented the assembly-films from inter-particle sintering. Fe-Pt nanoparticles of 4-5 nm in diameter were kept isolated physically and were chemically ordered after an optimum heat-treatment. However, higher temperature and longer time for the heat treatment were required to achieve proper chemical ordering to fit a specification of high-density recording media for future recording system. Fe-Pt nanoparticle assembly-films with a carbon overcoat annealed under the optimum conditions exhibited that the particle size was 4-5 nm and magnetic anisotropy constant was 4.8x10^7 erg/cm^3. Less

本研究的目的是建立铁-铂纳米颗粒阵列磁记录介质的制备技术，并评估其实现每平方英寸1万亿比特以上的面记录密度的潜力。研究结果如下：1)研究了Fe-Pt纳米颗粒粉末样品的化学有序性与磁各向异性之间的关系，发现穆斯堡尔谱估算的有序合金相体积比Q是评价化学有序性的有用参数。Q是短程有序化的参数，而S的X射线衍射法得到的是长程有序化的参数。在最大磁场为90kOE的情况下，评价了薄膜的磁各向异性。偏序Fe-PT纳米粒子的磁各向异性场H_k比几乎全有序的Fe-PT纳米粒子的分布要宽得多，并且低H_k组分以较高的体积比被包含。2)偏序Fe-Ptn…用微波辐射铁、铂盐多元醇还原法成功地制备出了更多的纳米粒子，而不需要任何合成后的热处理。在250℃的微波辐射下合成的Fe-铂纳米粒子的有序合金相体积比为60%，磁各向异性场大于80kO。3)将饱和脂肪酸(CnH&lt；2n&gt；O2)分子混合到Fe-铂纳米粒子悬浮液中有助于在纯水表面形成纳米粒子单分子膜，而不会发生混凝。由于铁-铂纳米粒子表面疏水，与水表面的界面能较高。脂肪酸分子可能降低了Fe-铂纳米颗粒单分子膜与水面之间的界面能，起到了缓冲作用。N[大于或等于]14的脂肪酸分子是形成规则纳米颗粒阵列的有效分子，而n=14的脂肪酸分子是形成规则纳米颗粒阵列的最佳分子。4)在Fe-PT纳米颗粒组装膜上溅射沉积的碳涂层有效地防止了组装膜的颗粒间烧结。直径为4-5 nm的Fe-铂纳米粒子在物理上保持隔离，经过优化的热处理后化学有序。然而，需要更高的温度和更长的热处理时间来实现适当的化学有序化，以适应未来记录系统对高密度记录介质的要求。在最佳工艺条件下制备的具有碳涂层的Fe-Pt纳米颗粒组装膜的颗粒尺寸为4-5 nm，磁各向异性常数为4.8×10~(-7)erg/cm~3。

项目成果

H.Sakuma, H.Nishio, Y.Kitamoto, et al.: "High-Field Torque Measurement of FePt Nanoparticles"Trans.Magn.Soc.Japan. 4,[1]. 24-27 (2004)

H.Sakuma、H.Nishio、Y.Kitamoto 等人：“FePt 纳米颗粒的高场扭矩测量”Trans.Magn.Soc.Japan。

High-Field Torque Measurement of FePt Nanoparticles

FePt 纳米颗粒的高场扭矩测量

• 发表时间: 2004
• 期刊: Trans.Magn.Soc.Japan vol.4,[1]
• 作者: H.Sakuma;H.Nishio;Y.Kitamoto;Y.Yamazaki;H.Yamamoto
• 通讯作者: H.Yamamoto

FePt Nanoparticle-assembly for Magnetic Recording Media

用于磁记录介质的 FePt 纳米颗粒组装体

• 发表时间: 2003
• 期刊: Magnetic Materials, Processes, and Devices VII and Electrodeposition of Alloys
• 作者: Yoshitaka Kitamoto;Hiroshi Sakuma;Arata Jogo;Tomoyasu Taniyama;Yohtaro Yamazaki
• 通讯作者: Yohtaro Yamazaki

Effect of Atomic Ordering on Magnetization Decay and Activation Volume of FePt Nanoparticles

原子有序度对 FePt 纳米颗粒磁化衰变和活化体积的影响

• 发表时间: 2003
• 期刊: IEEE Trans. on Magn. vol.39,[5]
• 作者: Hiroshi Sakuma;Hiroaki Nishio;Yoshitaka Kitamoto;Yohtaro Yamazaki;Hiroshi Yamamoto
• 通讯作者: Hiroshi Yamamoto

Hiroshi Sakuma, Hiroaki Nishio, Yoshitaka Kitamoto, et al.: "Effect of Atomic Ordering on Magnetization Decay and Activation Volume of FePt Nanoparticles"IEEE Trans.on Magn.. 39,[5]. 2758-2760 (2003)

Hiroshi Sakuma、Hiroaki Nishio、Yoshitaka Kitamoto 等人：“原子有序对 FePt 纳米颗粒磁化衰变和活化体积的影响”IEEE Trans.on Magn. 39，[5]。