Development of High Resolution Magnetic Force Microscopy with High Sensitivity and Low Noise and Its Application to Nano-scale Magnetic Imaging

高灵敏度、低噪声高分辨率磁力显微镜的研制及其在纳米级磁成像中的应用

• 批准号: 17360036
• 负责人: SAITO Hitoshi
• 金额: $ 9.66万
• 依托单位: Akita University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17360036/
• 关键词: Magnetic force microscopy; Magnetic domain observation; Spatial resolution; Low temperature MFM; MFM tip; Nano material; Magnetic recording media; 交換スプリング磁石; シミュレーション; 保磁力マッピング

Magnetic force microscopy (MFM) is widely used for magnetic domain observation. However the spatial resolution of commercial MFM is about several 10nm and is not enough to observe the recording bits of high density recording media. The purpose of this study is development of high resolution MFM and its application to nano-scale magnetic imaging. The following results were obtained.1. Development of high resolution MFM(1.1) Low noise MFM using tip coolingLow noise MFM was developed by adding the tip cooling equipment to high vacuum MFM. The noise of the MFM was reduced to the theoretical limit of thermodynamic noise of MFM cantilever by cooling a tip. The MFM can decrease the tip temperature and sample temperature to 42K and 32K, respectively. Low noise measuring condition can be obtained within 1 hour.(1.2) Fabrication of high resolution MFM tipsHigh-coercivity tip was fabricated by depositing FePt film on a surface oxidized Si tip made by O_2 plasma oxidation treatment and post-annealing of the tip. The coercivity of the tip is above 15 kOe and MFM resolution is about 10 nm. For further improvement of MFM resolution, a new high-resolution MFM tip using the cross section of an exchange-spring trilayer film [hard (low M_s) /soft (high M_s)/hard (low M_s)] was proposed and clarified the theoretical resolution is less than 5 nm by computer simulation. FePt/FeCo/FePt trilayers was fabricated for the application of MFM tip.2. Nano-scale magnetic imaging of high density magnetic recording mediaMedium noise-coercivity overlapping method was developed by using magnetic force microscopy and was used to study the origin of medium noise of 400~600 Gbit/inch^2 class perpendicular media. It was made clear that medium noise arises from (1) a spatial fluctuation of magnetization reversal filed in the media, where fluctuation length extends to about 100nm, (2) an insufficient magnetic field gradient of recording head.

磁力显微镜（MFM）广泛用于磁畴观察。然而商业MFM的空间分辨率约为几个10nm，不足以观察高密度记录介质的记录比特。本研究的目的是开发高分辨率磁力显微镜及其在纳米级磁成像中的应用。得到如下结果： 1．高分辨率MFM的开发 (1.1) 利用尖端冷却的低噪音MFM 在高真空MFM上添加尖端冷却装置，开发出低噪音MFM。通过冷却尖端，将 MFM 的噪声降低至 MFM 悬臂热力学噪声的理论极限。 MFM 可以将尖端温度和样品温度分别降低至 42K 和 32K。 1小时内即可获得低噪声的测量条件。(1.2)高分辨率MFM针尖的制作通过在经O_2等离子体氧化处理和针尖后退火制成的表面氧化Si针尖上沉积FePt薄膜来制备高矫顽力针尖。尖端的矫顽力高于15 kOe，MFM分辨率约为10 nm。为了进一步提高MFM分辨率，提出了一种利用交换弹簧三层薄膜[硬（低M_s）/软（高M_s）/硬（低M_s）]横截面的新型高分辨率MFM针尖，并通过计算机模拟阐明理论分辨率小于5 nm。制备了FePt/FeCo/FePt三层材料用于MFM针尖的应用。 2．高密度磁记录介质纳米级磁成像利用磁力显微镜开发了介质噪声-矫顽力重叠方法，用于研究400~600 Gbit/inch^2级垂直介质介质噪声的起源。已经明确，介质噪声产生的原因是(1)介质中磁化反转场的空间波动，波动长度延伸至约100nm，(2)记录头的磁场梯度不足。

项目成果

Fabrication of FePt/FeCo/FePt exchange spring trilayer with very thin FeCo layer for high resolution MFM tips

具有非常薄的 FeCo 层的 FePt/FeCo/FePt 交换弹簧三层的制造，用于高分辨率 MFM 尖端

• 发表时间: 2005
• 期刊: IEEE Trans. Magn. Vol.41, No.10
• 作者: Y.W.Rheem;H.Saito;S.Ishio
• 通讯作者: S.Ishio

Nanomaterial Engineering Compendium, Vol.2, Nano-metal

纳米材料工程纲要，第 2 卷，纳米金属

• 发表时间: 2005
• 作者: T. Hosoya;et. al.;Shunji Ishio
• 通讯作者: Shunji Ishio

Structural transition from L10 phase to A1 phase in FePt films caused by ion irradiation

• DOI: 10.1063/1.2177382
• 发表时间: 2006-03
• 期刊: Journal of Applied Physics
• 影响因子: 3.2
• 作者: T. Hasegawa;G. Li;W. Pei;H. Saito;S. Ishio;K. Taguchi;K. Yamakawa;N. Honda;K. Ouchi;T. Aoyama;I. Sato

Reduction of noise and fabrication of high-resolution tips for a high-resolution magnetic force microscope.

降低噪音并制造高分辨率磁力显微镜的高分辨率尖端。

• 发表时间: 2005
• 期刊: J.Magn.Soc.Jpn. Vol.29, No.8
• 作者: Hitoshi Saito;Takashi Natsume;Ryosuke Sunahara;Y.W.Rheem;Shunji Ishio
• 通讯作者: Shunji Ishio

磁気力顕微鏡用の磁性探針及びその製造方法

磁力显微镜用磁探针及其制造方法

• 发表时间: 2006