垂直磁记录介质材料的制备及翻转模式研究
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摘要
随着信息产业和互联网产业的高速发展,数据需求量越来越大。硬盘作为数据存储行业中最重要的部分已经不可替代,提高磁记录存储密度成为适应信息产业高速发展的途径之一。目前,商业化磁记录技术已经从水平磁记录顺利过渡到了垂直磁记录,存储密度超越了150 Gbit/in2,实验室范围内已经达到了614.4Gbit/in2。虽然离垂直磁记录的极限密度1-1.5 Tbit/in2已经近在咫尺,但记录密度的进一步提高仍然依赖于新的介质结构设计和新的记录技术的共同进步。制约垂直磁记录密度提高的主要因素是超顺磁效应,为了克服晶粒减小所带来的热扰动性的影响,需要寻找高磁晶各向异性的材料作为记录介质。寻找新的记录介质、改善已有记录介质的性能成为本文所研究的主要目的。
下面是本论文研究的主要内容：
1、高磁晶各向异性MnAl薄膜的研究：铁磁性τ-MnAl具有较高的磁晶各向异性常数(KU=1.7×107 erg/cm3),是理想的磁记录介质之一。本文研究主要是通过两个方面改善样品的磁性能。首先,利用制备楔形膜的方式来精确控制τ-MnAl产生的元素配比,并且通过观测其△M曲线研究MnAl颗粒间的相互作用方式和磁性翻转模式。其次,通过制备缓冲层引导后续薄膜生长,在得到较好τ-MnAl缓冲层的条件下,制备出了具有较好磁性能的τ-MnAl样品。
2、FePt基交换耦合结构和梯度型结构介质研究：虽然FePt具有很高磁晶各向异性,但其矫顽力较大,使记录信息很难写入。在保持热稳定性的条件下有效降低写入场是我们研究的主要目的。本文以L10-FePt为基础,通过溅射Fe和Co的方式来制备交换耦合结构和梯度型结构介质。结果证明两种材料均有效地降低了L10-FePt的矫顽力,并且显示较好的垂直特性。其次,讨论了硬磁软磁耦合翻转的两种理论模式,并且通过实验观测到了磁壁辅助磁化翻转模式,第一次从实验上得到了证实。
Nowadays, date storage has been progressing into a high level based on the great developing of information technology and internet systems.HDD has become the most important part of data storage industry and increasing the magnetic recording density is the best way to accommodate the information technology. Researching on high density magnetic recording concerns on both media materials and head technology. Till now, the recording technology has been changed from horizontal magnetic recording to perpendicular magnetic recording and its density has reached 614.4 Gbit/in2 in the laboratory. New technology should be induced to reach the limitation of perpendicular recording density which is 1-1.5Tbit/in2.The super-paramagnetic effect is the fundamental factor limiting the achievement of the goal. In order to conquer super-paramagnetic effect, it is necessary to explore new materials with high magneto-crystalline anisotropy. Exploring new materials and changing the properties of the materials we already have is the purpose of our study.
As the following, we summarize the main contents and results in this thesis.
I MnAl multilayer:
τ-MnAl has a magneto-crystalline anisotropy as high as 1.7×107 erg/cm3.It can be used as a candidate material in magnetic recording or devices. In two ways, we improve the magnetic properties of MnAl. Firstly, wedge-shaped multilayer has been used to investigate the appropriate portions of Mn and Al. The connection between magnetic grains and the magnetization reversal process was also investigated. Second, a buffer layer is used to induce the nucleation and growth of ferromagnetic phase. Theτ-MnAl with great magnetic properties has been prepared.
II ECC media and Graded media:
L10-FePt has large magneto-crystallize anisotropy which is good for thermal stability but bad for writability. In order to reduce the coercivity without lacking thermal stability, we have investigated exchange coupled composite media (ECC) and graded media. Fe layer and Co layer were deposited after the L10-FePt layer to form the ECC and graded media. The samples showed better magnetic properties with lower coercivity. All the samples have large squareness ratio along normal direction. Two magnetization reversal models are discussed. Domain wall motion model is revealed in our ECC samples.
下面是本论文研究的主要内容：
1、高磁晶各向异性MnAl薄膜的研究：铁磁性τ-MnAl具有较高的磁晶各向异性常数(KU=1.7×107 erg/cm3),是理想的磁记录介质之一。本文研究主要是通过两个方面改善样品的磁性能。首先,利用制备楔形膜的方式来精确控制τ-MnAl产生的元素配比,并且通过观测其△M曲线研究MnAl颗粒间的相互作用方式和磁性翻转模式。其次,通过制备缓冲层引导后续薄膜生长,在得到较好τ-MnAl缓冲层的条件下,制备出了具有较好磁性能的τ-MnAl样品。
2、FePt基交换耦合结构和梯度型结构介质研究：虽然FePt具有很高磁晶各向异性,但其矫顽力较大,使记录信息很难写入。在保持热稳定性的条件下有效降低写入场是我们研究的主要目的。本文以L10-FePt为基础,通过溅射Fe和Co的方式来制备交换耦合结构和梯度型结构介质。结果证明两种材料均有效地降低了L10-FePt的矫顽力,并且显示较好的垂直特性。其次,讨论了硬磁软磁耦合翻转的两种理论模式,并且通过实验观测到了磁壁辅助磁化翻转模式,第一次从实验上得到了证实。
Nowadays, date storage has been progressing into a high level based on the great developing of information technology and internet systems.HDD has become the most important part of data storage industry and increasing the magnetic recording density is the best way to accommodate the information technology. Researching on high density magnetic recording concerns on both media materials and head technology. Till now, the recording technology has been changed from horizontal magnetic recording to perpendicular magnetic recording and its density has reached 614.4 Gbit/in2 in the laboratory. New technology should be induced to reach the limitation of perpendicular recording density which is 1-1.5Tbit/in2.The super-paramagnetic effect is the fundamental factor limiting the achievement of the goal. In order to conquer super-paramagnetic effect, it is necessary to explore new materials with high magneto-crystalline anisotropy. Exploring new materials and changing the properties of the materials we already have is the purpose of our study.
As the following, we summarize the main contents and results in this thesis.
I MnAl multilayer:
τ-MnAl has a magneto-crystalline anisotropy as high as 1.7×107 erg/cm3.It can be used as a candidate material in magnetic recording or devices. In two ways, we improve the magnetic properties of MnAl. Firstly, wedge-shaped multilayer has been used to investigate the appropriate portions of Mn and Al. The connection between magnetic grains and the magnetization reversal process was also investigated. Second, a buffer layer is used to induce the nucleation and growth of ferromagnetic phase. Theτ-MnAl with great magnetic properties has been prepared.
II ECC media and Graded media:
L10-FePt has large magneto-crystallize anisotropy which is good for thermal stability but bad for writability. In order to reduce the coercivity without lacking thermal stability, we have investigated exchange coupled composite media (ECC) and graded media. Fe layer and Co layer were deposited after the L10-FePt layer to form the ECC and graded media. The samples showed better magnetic properties with lower coercivity. All the samples have large squareness ratio along normal direction. Two magnetization reversal models are discussed. Domain wall motion model is revealed in our ECC samples.
引文
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[2]http://www.sdd.toshiba.com.tw/news_detail.aspx?cid=All&id=P_00000049
[3]IDC report, Worldwide Hard Disk Drive 2008-2012 Forecast and Analysis-Shrugging off Storage Technology Challenges.IDC,2009.
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[6]J. G. Zhu, X. Zhu,and Y. Tang. Microwave assisted magnetic recording [J].IEEE Trans. Magn.,2008,44(1):125-131.
[7]S.Greaves, Y. Kanai, and H. Muraoka. Shingled recording for 2-3 Tbit/in2 [J]. IEEE Trans. Magn.,2009,45(10):3823-3829.
[8]R. Wood, M. Williams, A. Kavcic, and J. Miles. The feasibility of magnetic recording at 10 terabits per square inch on conventional media [J].IEEE Trans. Magn.,2009,45(2):917-923.
[9]K. Miura, E. Yamamoto, H. Aoi, and H. Muraoka. Estimation of maximum track density in shingled writing [J].IEEE Trans. Magn.,2009,45(10):3722-3725.
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[14]http://www.semi.cas.cn/kxcb/kpwz/200906/t20090619_2286722.html
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[30]C.Yanar, J. M. K. Wiezorek, V. Radmilovic, and W.A.Soffa. Massive transformation and the formation of the ferromagnetic L1(0) phase in manganese-aluminum-based alloys [J].Metall. Mater. Trans.A,2002,33(8): 2413-2423.
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[2]http://www.sdd.toshiba.com.tw/news_detail.aspx?cid=All&id=P_00000049
[3]IDC report, Worldwide Hard Disk Drive 2008-2012 Forecast and Analysis-Shrugging off Storage Technology Challenges.IDC,2009.
[4]E.D.Boerner, H. N. Bertram, and G.F. Hughes. Writing on perpendicular patterned media at high density and datarate [J].J. Appl. Phys.,1999,85(8): 5318-5320.
[5]M. A. Seigler, W. A. Challener, E. Gage, N. Gokemeijer, G. Ju, B.Lu, K. Pelhos, C.Peng, R. E. Rottmayer, X. Yang, H. Zhou, and T. Rausch. Integrated heat assisted magnetic recording head:Design and recording demonstration [J].IEEE Trans. Magn.,2008,44(1):119-124.
[6]J. G. Zhu, X. Zhu,and Y. Tang. Microwave assisted magnetic recording [J].IEEE Trans. Magn.,2008,44(1):125-131.
[7]S.Greaves, Y. Kanai, and H. Muraoka. Shingled recording for 2-3 Tbit/in2 [J]. IEEE Trans. Magn.,2009,45(10):3823-3829.
[8]R. Wood, M. Williams, A. Kavcic, and J. Miles. The feasibility of magnetic recording at 10 terabits per square inch on conventional media [J].IEEE Trans. Magn.,2009,45(2):917-923.
[9]K. Miura, E. Yamamoto, H. Aoi, and H. Muraoka. Estimation of maximum track density in shingled writing [J].IEEE Trans. Magn.,2009,45(10):3722-3725.
[10]戴传玮.磁控溅射薄膜生长的计算机模拟研究[D].上海：复旦大学,2009.
[11]曲喜心.薄膜物理[M].上海：上海科学技术出版社,1986.
[12]王立恒,黄运添,郑海涛.薄膜技术[M].北京：清华大学出版社,1991.
[13]郑伟涛.薄膜材料与薄膜技术[M].北京：化学工业出版社,1990.
[14]http://www.semi.cas.cn/kxcb/kpwz/200906/t20090619_2286722.html
[15]周上祺.X射线衍射分析：原理,方法,应用[M].重庆：重庆大学出版社,1991.
[16]麦振洪,贺楚光,崔树范.X射线双晶衍射摇摆曲线本征半峰宽的理论计算[J].物理学报,1990,39(5)：782-787.
[17]李朝荣,麦振洪,崔树范.晶体表面偏角对摇摆曲线及其半峰宽的影响[J]. 物理学报,1992,41(4)：603-608.
[18]宁永功,姬洪,王志红,刘爽.XRD摇摆曲线在单晶基片质量检测中的应用[J].现代仪器,1999,4：34-37.
[19]叶骏.磁性超薄膜磁光效应的研究[D].上海：复旦大学,2001.
[20]王芳,许小红.振动样品磁强计在磁记录介质中的应用[J].信息记录材料，2004,5(4)：46-50.
[21]李震,鄢俊兵,程伟明.磁记录介质晶粒磁相互作用参数△M及其测量方法[J].磁性材料器件,2008,39(4)：18-21.
[22]T Thomson, and K O'Grady. Magnetization reversal mechanisms and time-dependent processes in Tb-Fe-Co alloy films [J].J.Phys. D:Appl.Phys., 1997,30(11):1566-1576.
[23]T Thomson, K O'Grady, and G Bayreuther, Magnetization reversal mechanisms and time-dependent processes in thin Tb/Fe multilayer films [J].J.Phys. D: Appl. Phys.,1997,30(11):1577-1587.
[24]D. Weller, A. Moser, L. Folks. High K-u materials approach to 100 Gbits/in2 [J]. IEEE Trans. Magn.,2000,36(1):10-15.
[25]W. Van Roy, J. De Boeck, H. Bender. Structural and magnetic investigations of epitaxial ferromagnetic τ MnAl films grown on GaAs/AlAs by molecular-beam epitaxy [J].J. Appl. Phys.,1995,78(1):398-404.
[26]T. S.Chin. Permanent magnet films for applications in microelectro mechanical systems [J].J. Magn. Magn. Mater.,2000,209(1-3):75-79.
[27]J. D. Boeck, W. V.Roy, V. Motsnyi, Z. Liu, K. Dessein, G. Borghs. Hybrid epitaxial structures for spintronics [J].Thin Solid Films,2002,412(1-2):3-13.
[28]Y. C.Yang, W. W. Ho, C.Lin, J. L. Yang, H.M. Zhou, J. X. Zhu, X. X. Zeng, B. S.Zhang, and L. Jin. Neutron-diffraction study of hard magnetic alloy MnAlC [J].J. Appl.Phys.,1984,55(6):2053-2054.
[29]Q. Zeng, I. Baker, J. B.Cui, and Z. C.Yan.Structural and magnetic properties of nanostructured Mn-Al-C magnetic materials [J].J. Magn.Magn. Mater.,2007, 308(2):214-226.
[30]C.Yanar, J. M. K. Wiezorek, V. Radmilovic, and W.A.Soffa. Massive transformation and the formation of the ferromagnetic L1(0) phase in manganese-aluminum-based alloys [J].Metall. Mater. Trans.A,2002,33(8): 2413-2423.
[31]Q. Zeng,I. Baker, and Z. C.Yan. Nanostructured Mn-Al permanent magnets produced by mechanical milling [J].J.Appl.Phys.,2006,99(8):08E902.
[32]T. Sands, J. P. Harbison, M. L.Leadbeater, S.J.Allen, Jr.,G. W. Hull, R. Ramesh, and V.G. Keramidas.Appl. Phys.Lett., Epitaxial ferromagnetic tau-MnAl films on GaAs [J].1990,57(24):2609-2611.
[33]T. M. Rosier, Y.W. He, N.A. El-Masry. Ferromagnetic tau-MnAl epitaxially grown on(100) GaAs substrates by pulsed laser deposition [J].Materials Letters, 1996,26(4-5):227-231.
[34]A. Morisako, M. Matsumoto, and M. Naoe. Synthese of ferromagnetic tau-phase of Mn-Al films by sputtering [J].J. Appl. Phys.,1987,61(8):4281-4283.
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