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

讨论了垂直记录介质的磁特性和结构特性，以实现高热稳定性和低噪声性能。研究了颗粒-非晶混合介质的磁性能和记录性能。(1)在CoCr的颗粒型垂直介质的剩磁磁化率的角度依赖性表明，磁化反转发生相干旋转，并验证了使用的分析的基础上的Stoner-Wohlfarth模型。(2)实验和理论分析表明，对于厚度为20 nm、热稳定因子KuV/（kT）≥ 80的CoCr基颗粒型垂直介质，其剩余磁化率与颗粒各向异性场之比H r/H k的最大可达值为≤ 0.35。此外，为了实现接近1.0的大矩形度M_r/M_s，这是在低记录密度下抵抗热搅动效应所需的，我们发现垂直各向异性的值K_w需要比退磁能2πM_s^2大3倍以上。X射线衍射分析表明，抑制hcp结构中的结构缺陷，特别是在薄膜生长初期的缺陷，是CoCr基颗粒型介质中产生较大K_u值的关键。(3)CoPrTb成核型非晶薄膜的K_u值很大，即使在10 nm的薄膜厚度下也可达到4 × 10^6 erg/cm^3以上。然而，一个大的剩磁矫顽力没有成功地驱动在CoPrTb单层膜。(4)颗粒-无定形混合介质的信号与介质鼻S/Nm的比率比基于CoCr的颗粒型介质的信号与介质鼻S/Nm的比率高约10 dB（在300 kFRPI下）。此外，混合介质显示出极高的热稳定性。

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.