摘要
本研究以濺鍍法製作NdFeB 單層或多層膜。垂直異向性Nd-Fe-B 薄膜可藉由高溫鍍來達成; 高溫下濺鍍促進了柱狀晶結構的生長。此柱狀晶結構助長了Nd2Fe14B晶粒(105)方向上之織構,使得c-軸接近於垂直膜面之排列而得到垂直膜面異方性。至於薄膜的織構改變亦可藉由不同的底層材料來達成,例如: W, Mo, Cr, Pt/Ti/SiO2。本研究中,Cr底層促使Nd2Fe14B c-軸在水平方向排列而Pt/Ti/SiO2底層材料使得晶粒成等方性分布。而等方性的Nd-Fe-B薄膜可由室溫鍍膜再高溫後退火(550oC-700oC)得到。因此,薄膜方向性與Nd2Fe14B相的生成,均可在單層膜製程中控制,並得到良好磁性質。至於晶粒度大小對於磁性質的影響,本研究中利用多層膜的架構來實現。

(NdFeBx/Nbz)n多層膜藉由非磁性層Nb的間隔,使得晶粒度有效減小, 並顯著提昇矯頑磁力(Hc)。 當然適量的Nb添加,對於穩定Nd2Fe14B晶粒邊界與介面亦有很大助益,使得晶粒表面異向場的減小達到最少。對於(NdFeB25nm/Nb)16薄膜而言, 室溫下的矯頑磁力達到23kOe,其值遠大於相同製備過程中的NdFeB (400nm)單層薄膜9kOe。兩種薄膜的晶粒度分別為 24nm和167nm。部分Nd2Fe14B晶粒邊界富含Nb而且被隔絕,尤其是當Nb厚度增加, 此時現象更加顯著。

Nd-Fe-B, (NdFeB/Nb)n薄膜的矯頑機制, 藉由修正的微磁學模式來探討。藉由擬合的過程,可得到Nd-Fe-B, (NdFeB/Nb)n薄膜的微結構參數。 根據擬合的結果, 參數 aK 在0.37-0.70的範圍內, 此參數描述晶粒表面和邊界非均勻的異方向場。在參數 aK 和溫度無關的假設下, NdFeB薄膜的aK值大於0.3並證明了反向磁區孕核成長的機制。當然這些微結構參數都和材料的顯微組織有關, 例如: 介面層的擴散, 晶界的扭曲或二次相的析出, 都有可能貢獻於微結構參數 aK 和 Neff 。

Nd-Fe-B 薄膜的次磁滯迴路則呈現混合態的磁化模式, 並非顯著性的栓固型模型或孕核成長式模型。因此利用現象模型(phenomenological model) 來了解反向磁區的形成。至於磁區的形貌則由磁力顯微鏡觀察, 其所呈現的形貌為一交互作用磁區(Interaction domain),及一磁區中含數個晶粒, 磁區大小約50-100nm。因此反向磁區的成核和晶粒邊界分布有著大的關係。

第一章 簡介

納米晶材料研究的動力來自於不同晶粒尺度下之矯頑磁力。雙相納米晶材料的研究開發對於提高永磁材料之磁能積有很大幫助。藉由控制軟磁相晶粒度的大小使其在硬磁相磁區壁寬度的範圍,使得軟硬磁相間產生很強的交互耦合作用力,提高了殘留磁化量並保有高的矯頑磁力。薄膜製程是用以研製納米晶材料的方法之一,稀土-過渡元素硬磁薄膜的研究目的,在於降低尺寸並保有高的磁能積值,以期能在微機電系統中作為一薄膜磁鐵。

本章對於稀土-過渡元素永磁合金做了簡單的介紹。SmCo5, Sm2(Co,Fe,Cu,Zr)17 等高異方向性的強力磁鐵於1960-1980年問世,此為第一二代稀土永磁合金。1984年 第三代稀土永磁合金Nd2Fe14B 出現,其具有高磁異向性且於R2Fe14B合金中具高的飽和磁化量值,是目前室溫下最強的永久磁鐵。這期間出現的硬磁合金如NdFe11(Ti,Mo),

TbFe2 於磁伸縮中之應用, 非晶 TbDyFeCo材料於磁光材料之應用。到了1990-1993,有SmFe17N3 及雙相材料 NdFeB/Fe, SmCo/Co的誕生。至於稀土-過渡元素硬磁薄膜由1986年之單層膜至1997年後之多層膜研究。

本研究之目的在探討單層NdFeB與多層(NdFeB/Nb,Cr)n 薄膜之磁性。單層膜方面,藉由室溫與高溫鍍膜來製作等方與異方向性的薄膜,並藉由不同底材的效應來探討底層材料對織構生成的影響,此外藉由軟磁材料的添加來製作雙相薄膜。在多層膜方面,藉由單層NdFeB 厚度的變化來控制晶粒大小, 並有效的改變矯頑磁力, 並由Nb的介面層來穩定Nd2Fe14B晶粒邊界。

第二章 理論基礎與文獻回顧

本章引述微磁學的基本方程式,利用能量最小化推出非均質狀態下的最小孕核場。相關於理想孕核場的有關推導在本章中都有描述,例如均質成核場(Homogeneous model), Curling mode, Buckling mode。非均質成核場考慮材料本身微結構並非完美,所以利用以下三個參數來找出最小孕核場。(1) 由於晶粒表面的非均質化所造成磁異方向性衰減 (2) 考慮自發磁化量在空間場的分布, 藉由一傾斜外場來探討自發磁化方向與c-軸的夾角 (3) 考慮材料內部不同介質所造成的散場問題。

對於Nd2Fe14B材料之本質特性例如:室溫下在所有R2Fe14B化合物中具有高的飽和磁化量,其主要來源為不同佔位Fe原子3d軌域電子自旋磁矩之直接交互作用力。且其具有高的磁異方向性, 居禮溫度為314oC, 因此Nd2Fe14B 磁石為室溫下廣泛應用之磁石。其他關於Nd2Fe14B 磁石的性質, 在本章節中有所介紹。

第三章 實驗流程

本論文中有關於實驗步驟,實驗方法及各種磁學量測在本章中均有詳細的描述。本實驗主要利用濺鍍的方式來製備NdFeB 單層與 (NdFeB/Nb)n 多層膜,鍍膜主要區分為高溫與室溫下鍍膜,室溫下鍍膜則於高真空爐作後退火的工作。基板是採用Si(111), Si(100)單晶並按照IC 製程之步驟清洗。

有關於鍍膜後相的鑑定利用XRD作分析, 微結構則由高分辨電子顯微鏡HRTEM

來分析。室溫磁性量測由VSM來量測,其最大外場為2T, 低溫磁性質則由SQUID 或 DC 磁化率儀來作量測,其最大外場可大到7T。

有關於磁性物理上的量測包括:磁性後效量測(可求得活化體積,不可逆磁化率與磁黏滯係數),磁交互作用量測包括兩種不同磁化態的測量,一為DCD方式,一為IRM方式。

第四章 結果與討論

目前關於Nd-Fe-B, Sm-Co 稀土-過渡元素硬磁多層薄膜大都著墨於硬磁與軟磁層交替之多層架構如 NdFeB/Fe/ NdFeB, SmCo/Fe, 並探討其中硬磁/ 軟磁介面之交互作用力(Exchange Coupling Effect), 對於Nd-Fe-B, Sm-Co物系中以非磁性材料作為間隔層之多層膜架構目前僅有一篇文獻(NdFeB/W)n, 而本文即是以Nb, Cr 作為Nd-Fe-B 多層膜之間隔層, 並仔細探討製程參數對磁性質之影響, 其結果如下:

由XRD結果顯示, 初鍍(NdFeBx /Nbz)n多層膜為非晶質態, 但是間隔層Nb及保護層Cr為結晶態。經由高溫後退火後可形成Nd2Fe14B相, 其晶粒分布為等方向性的。以下探討不同製程變化下之多層膜磁性質。

1. 單層NdFeB厚度x nm 對於多層膜磁性質之影響。

首先固定NdFeB 的總厚度為400 nm, Nb 間隔層之厚度為5 nm, 熱處理溫度為670oC 20min(實際校正溫度631±3oC) 。

由VSM 室溫磁性之量測結果(最大外加場為2T)顯示, 隨著單層NdFeB 膜厚之減小, 其矯頑磁力有顯著提昇之現象。由x=200nm, n=2 的薄膜到x=25nm, n=16 之薄膜, 其矯頑磁力由9kOe提升至23kOe. 矯頑磁力提昇之因素為多層膜架構中Nd2Fe14B晶粒度減小所造成,當然對於適量Nb的添加亦有助於穩定Nd2Fe14B晶粒邊界,使得Nd2Fe14B晶粒表面磁異向場的破壞減小。

至於Nd2Fe14B晶粒度之觀察可由電子顯微鏡(TEM)得知。Nd2Fe14B晶粒度大小由x=200nm, n=2 之薄膜的167nm變化至x=25nm, n=16 之薄膜的 24nm。隨著晶粒度減小矯頑磁力有提昇之現象,至於晶粒度大小分布曲線,對於x=40nm, n=10之薄膜, 其晶粒分布為27nm-84nm, 相較於上述薄膜, x=25nm, n=16之膜, 具有較均勻的晶粒分布16nm-46nm。隨著單層Nd-Fe-B厚度的減小, 其角形比(remanence ratio)有下降的趨勢。對於等方性且完全孤立的晶粒(isolated grain)而言,其理想的角形比為0.5。因此多層NdFeB/Nb 薄膜, Nd2Fe14B 晶粒間具有很強之交互作用力使得角形比大於0.5. 但角形比由0.78 (x=200nm, n=2之薄膜) 降至0.42(x=20nm, n=20)之原因乃由於Nb 在介面處及晶粒邊界和NdFeB產生介面擴散和反應的比例隨單層NdFeB厚度的減小而增加因此部份Nd2Fe14B 晶粒會被Nb所包圍而降低了晶粒間之交互作用力。

由論文中薄膜之室溫下磁滯曲線圖,由圖可看出隨單層NdFeB厚度的減小其矯頑磁力有一倍的增加,但隨著Nb介面的增加,於反向磁化過程中會有一小階梯產生。此為Nb型態(可能為NbFeB或 NbFe2)之軟磁二次相所造成。由TEM圖中可看出Nb的分布情況。圖中於Nd2Fe14B晶粒中之黑色析出物(5nm)與沿層與層之介面處白色析出物(~27nm), 經與其他間隔層之薄膜對比,證實其為Nb所造成之析出物。至於飽和磁化量的遞減乃由於少量之Nb取代Fe的位置,影響了不同佔位中Fe與Fe間之直接交互用力,而減少了磁化量之貢獻。

2.Nb間隔層厚度對多層膜之影響。

隨著Nb間隔層厚度之增加,其Nb與NdFeB交互擴散的情況更為明顯, 由電子顯微鏡的照片可看出,有三至四層的Nd2Fe14B基地被Nb打破且包圍,因此被孤立的Nd2Fe14B晶粒數目增加。當Nb的厚度達到10nm時, Nd2Fe14B相無法生成,因此無法得到合理的矯頑磁力值。

3.單層與多層膜之比較。

相同製備條件與相同熱處理溫度下,同厚度的(NdFeB/Nb)n 多層膜比單層膜具有較高的矯頑磁力, 最主要因素乃由於Nb的間隔抑制了Nd2Fe14B晶粒之生長且穩定了Nd2Fe14B晶粒邊界。

4.異方向性薄膜之生長。

以上為經由後退火處理之等方向性單層與多層膜之探討。若於高溫下鍍膜,可得到柱狀晶的結構,此結構助長了Nd2Fe14B 的c-軸在接近於垂直膜面的方向上生長,因此薄膜具備有垂直膜面之異方向性。但經由底層材料之選擇可改變此織構。例如以Pt/Ti/SiO2為底層材料, 可使高溫下之鍍膜更趨於等方向性。

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英 文 摘 要
Single- and multi-layer NdFeB films were prepared by sputtering with or without a buffer layer or a spacer layer. Multi-layer (NdFeBx/Nbz)n films showed enhanced coercivity significantly due to the reduced grain size. For a (NdFeB25nm/Nb)16 film, room temperature coercivity is up to 23 kOe being much larger than the coercivity of NdFeB single-layer film (9 kOe) with the same thickness of 400nm prepared under the same conditions. The average grain size changes from 24nm to 167nm. Some Nd2Fe14B grains are enriched by Nb and isolated as the thickness of spacer layer Nb increases, at annealing temperature 628oC.

Perpendicular anisotropic Nd-Fe-B film can be obtained as deposited at high temperature. High deposition temperature enhances the growth of columnar grain structure. Texture of films can be changed with different underlayer such as W, Mo, Cr, or Pt. Isotropic Nd-Fe-B films can be obtained by depositing at room temperature followed by post annealing at high vacuum.

Coercivity mechanism of Nd-Fe-B, (NdFeB/Nb)n films were discussed by modified micromagnetic models. That is to say the testimony of the microstructure parameters of the Nd-Fe-B, (NdFeB/Nb)n films. According to the fitted results, the range of aK, describing the inhomogeneities of anisotropy at grain surface and boundary varied from 0.37-0.70. The value of aK larger than 0.3 and exhibit the nucleation mechanism of NdFeB films under the assumption of temperature independent aK. Microstructure parameter was also related to the observed microstructure. Interdiffusion, distortion of grain boundary or second phase precipitation contribute to the value of microstructure parameters aK and Neff .

Minor loops of NdFeB films exhibit the mixed type magnetization behavior. Neither exactly the pinning type nor nucleation type mechanism. Therefore the pheno- menological model was used to understand the formation of reversed domain. Domain pattern was investigated by MFM and found to be in the dimension about 50-100nm.

References :
[1] G.C. Hadjapanayis, Nanophase hard magnets, J. Magn. Magn. Mater, 200 (1999) 373-391.
[2] C. Sunyanarayana, Nanocrystalline materials, International Materials Reviews, 40 (1995) 41.
[3] G. Bate, Nanophase Materials, J. Magn. Magn. Mater, 100 (1991) 413.
[4] S. Starroyiannis, I. Panagiotopoulos, D. Niarchos, J. Christodoulides, Y. Zhang, G.C. Hadjapanayis, Appl. Phys. Lett. 73 (1998) 3453.
[5] J.J Delaunay, T. Hayashi, M. Tomita, S. Hirono, S. Umemura, Appl. Phys. Lett, 71 (1997) 3427.
[6] F.J. Cadieu, T. D. Cheung, S.H. Aly, L. Wickramasekara and R.G. Pirich, IEEE Trans. Magn. MAG-19 (1983) 2038.
[7] F.J. Cadieu, T. D. Cheung, L. Wickramasekara and N. Kamprath, High Hc perpendicular anisotropy Nd-Fe-B sputtered films, IEEE Trans. Magn. MAG-22 (1986) 752.
[8] M. Levy, R.M. Osgood, H. Hegde, F.J. Cadieu, R. Wolfe and V.J. Fratello, Integrated optical isolators with sputtered-deposited thin-film magnets, IEEE Photonic Technology Letters. 8 (1996) 903.
[9] M. Levy, R. Scarmozzino and R.M. Osgood, R. Wolfe, F.J. Cadieu, Permanent magnet film magneto-optic waveguide isolator, J. Appl. Phys. 75 (1994) 6286.
[10] F.J. Cadieu, High coercivity force and large remanent moment magnetic films with special anisotropies, J. Appl. Phys. 61 (1987) 4105.
[11] K.D. Aylesworth, Z.R. Zhao, D.J. Sellmyer, G.C. Hadjipanayis, Growth and control of the microstructure and magnetic properties of sputtered Nd2Fe14B films and multilayers, J. Magn. Magn. Mater, 82 (1989) 48-56.
[12] B.A. Kapitanov, N.V. Kornilov, Ya.L. Linetsky and V.Yu. Tsvetkov, Sputtered permanent Nd-Fe-B magnets, J. Magn. Magn. Mater, 127 (1993) 289-297.
[13] Eric E. Fullerton, C.H. Sowers, X.Z. Wu and S.D. Bader, Growth of oriented rare-earth-transition-metal thin films, IEEE Trans. Magn. 32 (1996) 4434.
[14] D.J. Keavney, Eric E. Fullerton, J.E. Pearson and S.D. Bader, Magnetic properties of c-axis textured Nd2Fe14B thin films, IEEE Trans. Magn. 32 (1996) 4440.
[15] Stefan M. Parhofer, Joachim Wecker, Christian Kuhrt, Gunter Gieres, Remanence enhancement due to exchange coupling in multilayers of hard- and softmagnetic phases, IEEE Trans. Magn. 32 (1996) 4437.
[16] Ivan K. Schuller, S. Kim, C. Leighton, Magnetic superlattices and multilayers, J. Magn. Magn. Mater, 200 (1999) 571-582.
[17]
D.J. Mapps, R. Chandrasekhar, K.O. Grady, Magnetic Properties of NdFeB thin films on Platinum Underlayers, IEEE Trans. Magn. 33 (1997) 3007.
[18] H. Sun, T. Tomida, S. Hirosawa, Y. Maehara, Magnetic properties and microstructure studies of Nd-Fe-B thin films, J. Magn. Magn. Mater, 164 (1996) 18-26.
[19] J. F. Herbst, R2Fe14B materials: Intrinsic properties and technological aspects, Reviews of Modern Physics, 63 (1991) 819.
[20] Herbst, J. F., J. J. Croat, F. E. Pinkerton, and W. B. Yelon, Phys. Rev. B 29, (1985) 4176.
[21] A. H. Morrish, The Physical Principles of Magnetism, Wiley, New York, 1965.
[22] Eckart F. Kneller, The Exchange-Spring Magnet: A New Material Principle for Permanent Magnets, IEEE Trans. Magn. 27 (1991) 3588.
[23] J. L. Tsai, T. S. Chin, S. K. Chen and J. C. Shih, Magnetic properties and growth behavior of Nd-Fe-B films on Si(111), Jpn. J. Appl. Phys. 38 (1999) 4051-4055.
[24] D. Wang, G. C. Hadjipanayis and D. J. Sellmyer, Magnetization of Sm-Fe-N thin films with in-plan anisotropy, IEEE Trans. Magn. 28 (1992) 2590.
[25] M. R. Jian, T. S. Chin, J. L. Tsai, H. W. Zhang, B. G. Shen, Structure and magnetic properties of textured Nd(Fe,Ti)12Nx films, J. Magn. Magn. Mater, 209 (2000) 205-207.
[26] S. Y. Zhang, Z. S. Shan, Y. Liu, D. J. Sellmyer, High coercivity SmFeSiC films fabricated by multilayer sputtering, IEEE Trans. Magn. 32 (1996) 4550.
[27] M. N. Baibich, J. M. Broto, A. Fert, F. Nguyen Van Dau, F. Petroff, P. Etienne, G. Creuzet, A. Friederich, J. Chazelas, Phys. Rev. Lett. 61 (1988) 2472.
[28] J. W. H. duMond, J. P. Youtz, Phys. Rev. 48 (1935) 703.
[29] Eric E. Fullerton, J. S. Jiang, S. D. Bader, Hard/soft magnetic heterostructure: model exchange-spring magnets, J. Magn. Magn. Mater, 200 (1999) 392-404.
[30] H. Kronmuller, Micromagnetic background of hard magnetic materials, Supermagnets, Hard Magnetic Materials, 461-498.
[31] Alex Hubert, Magnetic domains, Springer-Verlag Berlin Heidelberg New York, 118.
[32] M. Seeger, J. Bauer, H. Kronmuller, J. Bernardi, J. Fidler, Magnetic and microstructural properties of sintered FeNdB-based magnets with Ga and Nb additions, J. Magn. Magn. Mater, 138 (1994) 294-300.
[33] H. Kronmuller, K. D. Durst and G. Martinek, Angular dependence of the coercivity field in sintered Fe77Nd15B8 Magnets, J. Magn. Magn. Mater, 69 (1987) 149-157.
[34] G. Martinek and H. Kronmuller, Influence of grain orientation on the coercivity field in Fe-Nd-B permanent magnets, J. Magn. Magn. Mater, 86 (1990) 177-183.
[35] H. Kronmuller, K. D. Durst, M. Sagawa, Analysis of the magnetic hardening mechanism in RE-FeB permanent magnets, J. Magn. Magn. Mater, 74 (1988) 291-302.
[36] Herbst, J. F., J. J. Croat, and W. B. Yelon, 1985, J. Appl. Phys. 57 (1991) 4086.
[37] G. C. Hadjipanayis, W. Gang, J. Appl. Phys. B4 (1988) 5559.
[38] F. M. Ahmed, D. S. Edgley and I. R. Harris, Effect of niobium addition on the Nd-Fe-B alloy and magnet, Journal of Alloys and Compounds, 209 (1994) 363-368.
[39] Shao-Xiong Zhou, P. Johansson, S. J. Savage and Li-Ya Cui, Effect of Ga, Si and Nb additions on the phases and magnetic properties of melt-spun Nd-Fe-B alloys, IEEE Trans. Magn. 26 (1990) 1739.
[40] T. Shima, A. Kamegawa, E. Aoyagi, Y. Hayasaka, H. Fujimori, Magnetic properties and structure of Nd-Fe-B thin films with Cr and Ti underlayers, J. Magn. Magn. Mater, 177-181 (1998) 911-912.
[41] T. Shima, A. Kamegawa, H. Fujimori, Enhanced coercive force of Nd-Fe-B thin films by the introduction of a Cr underlayer, Journal of Alloys and Compounds 281 (1998) 46-49.
[42] Y. Okumura, H. Fujimori, O. Suzuki, N. Hosoya, X. B. Yang and H. Morita, Magnetic properties and microstructure of sputtered CoSm/X(X=Ti, V, Cu and Cr) thin films, IEEE Trans. Magn. 30 (1994) 4038.
[43] M. Imakawa, S. Ishibashi, M. Kuwabara, T. Shimatsu, M. Takahashi, High coercivity force and low intergranular coupling in CoCrTa thin films recording media fabricated under ultra clean sputtering process, J. Magn. Magn. Mater. 182 (1998) 403-412.
[44] J. E. Witting, T. P. Nolan, C. A. Ross, M. E. Schabes, K. Tang, R. Sinclair, J. Bently, Chromium Segregation in CoCrTa/Cr and CoCrPt/Cr thin films for longitudinal recording media, IEEE Trans. MAG-34, No.4 (1998) 1564.
[45] G. Choe, Effect of film morphology on grain boundary segregation induced magnetic properties in heated treated CoCrPt/Cr films, IEEE Trans. MAG-31, No. 6 (1995) 2809.
[46] J. L. Tsai and T. S. Chin, Interface effect of Nd(Dy)FeB/X/Si (X=W, Mo, Pt) films, Proceeding of the Fifteenth International Workshop on Rare-Earth Magnets and Their Application, (1998) pp. 1057.
[47] S. Parhofer, G. Gieres, J. Wecker, L. Schultz, Growth characteristics and magnetic properties of sputtered Nd-Fe-B thin films, 163 (1996) 32-38.
[48] H. Lemke, S. Muller, T. Goddenhenrich and C. Heiden, phys. stat. Sol. (a) 150 (1995) 723.
[49] K. D. Aylesworth, Z. R. Zhao, D. J. Sellmyer and G. C. Hadjipanayis, Growth and control of the microstructure and magnetic properties of sputtered Nd2Fe14B films and multilayers, J. Magn. Magn. Mater. 82 (1989) 48-56.
[50] S. Yamashita and J. Yamasaki, M. lkeda and N. lwabuchi, Anisotropic Nd-Fe-B thin-film magnets for milli-size motor, J. Appl. Phys. 70(10) (1991) 6627.
[51] J. L. Tasi, T. S. Chin and S. K. Chen, Coercivity Mechanism and Microstructure Study of Sputtered Nd-Fe-B/X/Si(111) (X=W, Pt) Films, Jpn. J. Appl. Phys. vol. 38 (1999) 5879-5884.
[52] D. J. Keavney, Eric E. Fullerton, J. E. Pearson and S. D. Bader, Magnetic properties of c-axis textured Nd2Fe14B thin films, IEEE Trans. Vol. 32 (1996) 4440.
[53] I. Panagiotopoulos, X. Meng-Burany, G.C. Hadjapanayis, Granular Nd2Fe14B /W thin films, J. Magn. Magn. Mater, 172 (1997) 225-228.
[54] M. J. O'Shea, P. Perera, J. Appl. Phys. 76(10) (1994) 6174.
[55] N. B. Shevchenko, A. S. Murthy, G. C. Hadjapanayis, Mater. Sci. Eng. A 204 (1995) 39.
[56] H. Wan, A. Tsoukatos, Y. J. Zhang, G. C. Hadjapanayis, S. I. Shah, Nanostructured Materials 1 (1992) 505.
[57] F. J. Cadieu, High coercivity force and large remanent moment magnetic films with special anisotropies, J. Appl. Phys. 61(8) (1987) 4105.
[58] B. A. Kapitanov, N. V. Kornilov, Ya. L. Linetsky and V. Yu. Tsvetkov, Sputtered permanent Nd-Fe-B magnets, J. Magn. Magn. Mater, 127 (1993) 289-297.
[59] S. Parhofer, C. Kuhrt, J. Wecker and G. Gieres and L. Schultz, Magnetic properties and growth texture of high-coercivity Nd-Fe-B thin films, J. Appl. Phys. vol. 83 (1998) 2735.
[60] Milton. Ohring, The Materials Science of Thin Films, Academic Press INC. Harcourt Brace & Company, Publishers. (1992) 224.
[61] T. Shima, A. Kamegawa, H. Fujimori, Enhanced coercive force of Nd-Fe-B thin films by the introduction of a Cr underlayer, J. Alloys and Compounds. 281 (1998) 46-49.
[62] T. Shima, A. Kamegawa, H. Fujimori, Magnetic properties and structure of Nd-Fe-B thin films with Cr and Ti underlayers. 177-181 (1998) 911-912.
[63] I. Panagiotopoulos, X. Meng-Burany, G.C. Hadjapanayis, Granular Nd2Fe14B /W thin films, J. Magn. Magn. Mater, 172 (1997) 225-228.
[64] S. Parhofer, C. Kuhrt, J. Wecker and G. Gieres, Magnetic properties and growth texture of high-coercive Nd-Fe-B thin films, J. Appl. Phys, vol. 83 (1998) 2735-2741.
[65] H. Sun, T. Tomida, S. Hirosawa, Y. Maehara, Magnetic properties and microstructure studies of Nd-Fe-B thin films, J. Magn. Magn. Mater, 164 (1996) 18-26.
[66] S. Yamashita, J. Yamasaki, M. Ikeda and N. Iwabuchi, Anisotropic Nd-Fe-B magnets for milli-size motor, J. Appl. Phys, 70 (1991) 6627-6629.
[67] Wei Tang, Zhi-Qiang Jin, Jian-Ron Zhang, Effect of composition on cryatalline texture and magnetic properties of Nd2Fe14B thin films, J. Magn. Magn. Mater, 185 (1998) 241-245.
[68] D. Goll, M. Seeger, H. Kronmuller, Magnetic and microstructural properties of nanocrystalline exchange coupled PrFeB permanent magnets, J. Magn. Magn. Mater, 185 (1998) 49-60.
[69] M. Shindo, M. Ishizone and T. Miyazaki, Magnetic properties of exchange-coupled a-Fe/Nd-Fe-B multilayer thin film magnets, J. Appl. Phys, 81 (1997) 4444-4446.
[70] M. Ishizone, H. Kato, T. Shindo and A. Sakuma, Fabrication and Magnetic Properties of Exchange-Coupled Nd-Fe-B/Fe Nanocomposite Thin Films, J. Magn. Soc. Japan 23 (1999) 282-284.
[71] G. Martinek, H. Kronmuller, Influence of grain orientation on the coercive field in Fe-Nd-B permanent magnets, J. Magn. Magn. Mater, 86 (1990) 177-183.
[72] S. Hock. Ph. D. thesis, Universitat Stuttgart (1988).
[73] J. Bauer, M. Seeger, H. Kronmuller, Magnetic properties and microstructural analysis of rapidly quenched FeNdBGaNb permanent magnets, J. Magn. Magn. Mater, 139 (1995) 323-324.
[74] R. Fisher, T. Schrefl, H. Kronmuller, J. Fidler, Grain-size dependence of remanence and coercive field of isotropic nanocrystalline composite permanent magnets, J. Magn. Magn. Mater, 153 (1996) 35-49.
[75] X. C. Kou, H. Kronmuller, D. Givord and M. F. Rossignol, Coercivity mechanism of sintered Pr17Fe75B8 and Pr17Fe53B30 permanent magnets, Physical Review B 50 (1994) 3849-3860.
[76] H. Kronmuller, Micromagnetism and the microstructure of modern magnetic materials, Magnetic Hysteresis in Novel Magnetic Materials, (1997) 85-108.
[77] R. W. Gao, D. H. Zhang, W. Li, X. M. Li, J. C. Zhang, Hard magnetic properties and dM plot for sintered NdFeB magnet, J. Magn. Magn. Mater, 208 (2000) 239-243.
[78] I. Panagiotopoulos, L. Withanawasam, G. C. Hadjipanayis, Exchange spring behavior in nanocomposite hard magnetic materials, J. Magn. Magn. Mater, 152 (1996) 353-358.
[79] K. O'Grady, M. El-Hilo and R. W. Chantrell, IEEE Trans. Magn. 29 (1993) 2608.
[80] Eckart F. Kneller, The Exchange-Spring Magnet: A New Material Principle for Permanent Magnets, IEEE Trans. Magn. 27 (1991) 3588-3600.
[81] F. M. Ahmed, D. S. Edgley and I. R. Harris, Effect of niobium addition on the Nd-Fe-B alloy and magnet, J. Alloys and Compounds, 209 (1994) 363-368.
[82] W. Rodewald and B. Wall, Structure and Magnetic Properties of Sintered Nd-Fe-Nb-B Magnets, J. Magn. Magn. Mater, 80 (1989) 57-60.
[83] M. Sagawa et al., Japan. J. Appl. Phys. 6 (1987) 785.
[84] Shao-Xiong, P. Johansson, S. J. Savage and Li-Ya Cui, Effect of Ga, Si and Nb additions on the phases and magnetic properties of melt-spun Nd-Fe-B alloys, IEEE Trans. Magn. 26 (1990) 1739-1741.
[85] Liu Jinfang, Luo Helie and Wan Jiang, Magnetic properties and electron microscopy analysis of Nb-containing (NdDy)FeB sintered magnets, J. Magn. Magn. Mater. 103 (1992) 65-72.
[86] J. Q. XIE, C. H. Wu, Y. C. Chuang, F. M. Yang, Effect of Ga and Nb Addition on the Magnetic Properties of the Nd2(Fe,Co)14B compound, J. Magn. Magn. Mater. 75 (1988) 361-365.
[87] J. J. Wang, F. J. Cadieu, et., al, Dry Etch Patterning of LaCaMnO3 and SmCo Thin Films, J. Electrochem. Soc., 145 (1998) 2512-2515.
[88] Milton. Ohring, The Materials Science of Thin Films, Academic Press INC. Harcourt Brace & Company, Publishers. (1992) 390.
[89] D. J. Keavney, Eric E. Fullerton, J. E. Pearson and S. D. Bader, Magnetic Properties of c-axis Textured Nd2Fe14B Thin Films, IEEE Trans. Magn. 32 (1996) 4440-4442.

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