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Spin-cluster recording media for high-density magnetic recording.

用于高密度磁记录的自旋簇记录介质。

基本信息

批准号：
11305027
负责人：
NAKAMURA Yoshihisa
金额：
$ 26.24万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11305027/
关键词：
High density magnetic recording Perpendicular magnetic recording Spin cluster Nucleation-type of recording media Remanence coercivity Thermal stability Perpendicular magnetic anisotropy

项目摘要

Magnetic and structural properties of perpendicular recording media required to achieve both high thermal stability and low-noise performance are discussed. Moreover magnetic properties and recording performances of granular-amorphous hybrid media are examined.(1) The angular dependence of remanence coercivity in CoCr based granular-type of perpendicular media indicated that magnetization reversal occurs by coherent rotation, and validates the use of an analysis based on the Stoner-Wohlfarth model.(2) Experimental and theoretical analysis revealed that for CoCr based granular-type of perpendicular media of 20 nm thickness having the thermal stability factor K_uV/(kT)〜80, the maximum achievable value of the ratio of remanence coercivity to anisotropy field of grains, H_r/H_k, is 〜0.35. Furthermore, in order to realize a large squareness M_r/M_s of nearly 1.0, which is required to resist the thermal agitation effect at low recording density, we find that the value of perpendicular anisotropy, K_w is needs to be more than 3 times larger than the demagnetizing energy 2πM_s^2. X-ray diffraction patterns suggested that the suppression of structural imperfections in the hcp structure, particularly in the initial film growth, is the key issue to induce larger K_u value in the CoCr based granular-type of media.(3) CoPrTb nucleation-type of amorphous film showed a large K_u value of 4x10^6 erg/cm^3 or more even at thin film of 10 nm. However, a large remanence coercivity was not successfully driven in CoPrTb single layer films.(4) The ratio of signal to media-nose S/Nm of granular-amorphous hybrid media was about 10 dB higher than that of CoCr based granular-type of media (at 300 kFRPI). Moreover, the hybrid media showed extremely high thermal stability.

讨论了实现高热稳定性和低噪声性能所需要的垂直记录介质的磁性和结构特性。研究了颗粒-非晶杂化介质的磁性能和记录性能。(1)基于CoCr的颗粒型垂直介质中剩磁矫顽力的角依赖性表明，磁化反转是通过相干旋转发生的，并验证了基于Stoner-Wohlfarth模型的分析。(2)实验和理论分析表明，在热稳定系数K_uV/(kT) ~ 80的20 nm厚度的CoCr基颗粒型垂直介质中，残余矫顽力与晶粒各向异性场之比H_r/H_k的最大可达值为~ 0.35。此外，为了实现在低记录密度下抵抗热搅拌效应所需的接近1.0的大方形度M_r/M_s，我们发现垂直各向异性K_w的值需要大于退磁能量2πM_s^2的3倍以上。x射线衍射图表明，抑制hcp结构中的结构缺陷，特别是在初始膜生长过程中，是在CoCr基颗粒型介质中诱导较大K_u值的关键问题。(3) CoPrTb成核型非晶态薄膜在10 nm时K_u值也较大，可达4 × 10^6 erg/cm^3以上。然而，在CoPrTb单层薄膜中，没有成功地驱动大的剩磁矫顽力。(4)在300 kFRPI时，颗粒-非晶混合介质的信号与介质的比值S/Nm比基于CoCr的颗粒型介质高约10 dB。此外，混合介质表现出极高的热稳定性。