纳米磁性薄膜的电化学制备、表征及其磁性能研究
摘要
本论文前一部分采用控电位双脉冲技术,在P型单晶硅(111)面上电沉积制备了一系列的[Co(1.5nm)/Cu(t)]100(0.9nm 本论文后一部分采用恒流电沉积方法,接着在半导体硅片上制备不同组分的Cu-Co颗粒膜,并对其进行高温退火处理。制备态各样品的巨磁电阻值均比较小。正交实验得出450℃为最佳退火温度,最佳退火时间为一小时。颗粒膜巨磁电阻值随Co浓度呈现出先增大后减小的趋势,当镀层组成为Co20Cu80时,450℃退火后得到最大巨磁电阻值为8.21%。当Co浓度大于40%后,由于阈渗效应,GMR值急剧降低。
XRD测试结果表明,在研究的钴浓度范围内,制备态样品形成了单相亚稳态面心立方结构,并以(111)面为择优生长面,当镀层组成为Cu80Co20时,(111)面的择优取向系数达到最大。制备态样品的晶格常数随Co浓度的增大近似遵循线性规律变化。随着退火温度的升高,样品的晶面间距和晶格常数逐渐增大。600℃退火后样品的XRD谱图中开始出现金属Co的衍射峰,700℃退火后(111)和(200)面分别分离成单金属Cu和单金属Co的衍射峰,相分离完全。700℃退火后Co20Cu80样品的TEM测试得出:SAED结果为一系列的衍射环,表明薄膜为多晶结构; 暗场像图中得到析出的金属Co颗粒镶嵌于薄膜中,颗粒平均尺寸为5-20nm。制备态Co20Cu80样品的磁滞回线接近于超顺磁性物质的磁滞回线,随着退火温度的升高,样品的矫顽力、剩余磁化强度、饱和磁化强度等参数逐渐增大,发生了从超顺磁性到铁磁性的转变。对磁化强度的计算结果也证实了退火过程中发生的变化。
A series of [Co(1.5nm)/Cu(t)]100(0.9nm Cu-Co granular alloys with different Co content were electrodeposited onto Si substrates by galvanostatic mode in the latter part of the paper, and subjected to high temperature annealing. The values of GMR of the as-deposited films were small. The results of the orthogonal experiment revealed that 450℃ was the optimal annealing temperature and the optimal annealing time was found to be one hour. GMR increases first, and then decreases with the increase of Co content in the granular films. It was found that the maximun GMR value reach 8.21% for the Co20Cu80 film after annealing at 450℃ for one hour. The values of GMR decrease dramatically when the Co concentration x>0.40 can be explained by the percolation mechanism.
The XRD result showed that the as-deposited films form metastable alloy structure and has the predominant orientation of (111) crystal plane in the studied Co concentration range. The orientation factor of (111) crystal plane reached maximum for the Co20Cu80 film. The fcc lattice parameterαof the single phase fcc alloy changed linearly with Co concentration. The plane distance and lattice parameter increased with annealing temperature. The diffraction peak of pure Co was first observed in the XRD spectrum of 600℃ annealed sample. The (111) and (200) peaks split into diffraction peak of pure Cu and pure Co in the diffractogram of the 700℃annealed sample, indicating phase separation occurred upon annealing. The structure of the 700℃ annealed Co20Cu80 film was characterized by TEM: the SAED result was found to be diffraction rings. The magnetic Co particles was found in the dark-field image and its in the range 5-20nm. The hysteresis loop of the as-deposited sample was close to superparamagnetic material. The value of coercivity(Hc), remanent magnetization(Mr), saturation magnetization(Ms) increased with annealing, indicating the change from superparamagnetic to ferromagnetic contribution to the GMR effect. The calculation result of magnetization also verified this change.
XRD测试结果表明,在研究的钴浓度范围内,制备态样品形成了单相亚稳态面心立方结构,并以(111)面为择优生长面,当镀层组成为Cu80Co20时,(111)面的择优取向系数达到最大。制备态样品的晶格常数随Co浓度的增大近似遵循线性规律变化。随着退火温度的升高,样品的晶面间距和晶格常数逐渐增大。600℃退火后样品的XRD谱图中开始出现金属Co的衍射峰,700℃退火后(111)和(200)面分别分离成单金属Cu和单金属Co的衍射峰,相分离完全。700℃退火后Co20Cu80样品的TEM测试得出:SAED结果为一系列的衍射环,表明薄膜为多晶结构; 暗场像图中得到析出的金属Co颗粒镶嵌于薄膜中,颗粒平均尺寸为5-20nm。制备态Co20Cu80样品的磁滞回线接近于超顺磁性物质的磁滞回线,随着退火温度的升高,样品的矫顽力、剩余磁化强度、饱和磁化强度等参数逐渐增大,发生了从超顺磁性到铁磁性的转变。对磁化强度的计算结果也证实了退火过程中发生的变化。
A series of [Co(1.5nm)/Cu(t)]100(0.9nm
The XRD result showed that the as-deposited films form metastable alloy structure and has the predominant orientation of (111) crystal plane in the studied Co concentration range. The orientation factor of (111) crystal plane reached maximum for the Co20Cu80 film. The fcc lattice parameterαof the single phase fcc alloy changed linearly with Co concentration. The plane distance and lattice parameter increased with annealing temperature. The diffraction peak of pure Co was first observed in the XRD spectrum of 600℃ annealed sample. The (111) and (200) peaks split into diffraction peak of pure Cu and pure Co in the diffractogram of the 700℃annealed sample, indicating phase separation occurred upon annealing. The structure of the 700℃ annealed Co20Cu80 film was characterized by TEM: the SAED result was found to be diffraction rings. The magnetic Co particles was found in the dark-field image and its in the range 5-20nm. The hysteresis loop of the as-deposited sample was close to superparamagnetic material. The value of coercivity(Hc), remanent magnetization(Mr), saturation magnetization(Ms) increased with annealing, indicating the change from superparamagnetic to ferromagnetic contribution to the GMR effect. The calculation result of magnetization also verified this change.
引文
1,刘吉平,郝向阳,纳米科学与技术,北京:科学出版社,2002:202
2,刘吉平,郝向阳,纳米科学与技术,北京:科学出版社,2002:134-143
3,曹茂盛,关长斌,徐甲强,纳米材料导论,哈尔滨:哈尔滨工业大学出版社,2001:51
4,陈志军,王皓,傅正义,巨磁电阻材料研究进展,材料导报,2001,15(12):22
5,都有为, 纳米微粒系统中的巨磁电阻效应,物理,1997,26(10):627 –630
6,王宝军,颗粒膜的巨磁电阻效应,凉山大学学报,2003,5(2):18-21
7,都有为,磁性颗粒膜研究概况,金属功能材料,1995,4(5):122-124
8,M. N.Baibich,J.M.Brato, A.Fert, et al, Giant Magnetoresistance of (001)Fe/(001)Cr Magnetic Superlattices, Phys Rev.Lett, 1988, 61: 2472
9 , A.E.Berkowitz, J.R.Mitchell, M.J.Carey, et al, Giant magnetoresistance in heterogenous Cu-Co alloys, Phys.Rev.Lett, 1992, 68: 3749
10,J.Q.Xiao, J.S.Jieng, and C.L.Chien, Perpendicular magnetic anisotropy of Co–Ag granular thin films, Phys Rev Lett, 1992, 61: 1855
11,谢秉川,颗粒膜中的巨磁阻效应,广西师院学报,1999,16(4):27-32
12,都有为,纳米材料中的巨磁电阻效应,物理学进展,1997,17(2):180-181
13,张寿柏,蔡炳初,杨春生等,Co-Cu 合金颗粒膜的室温磁电阻效应,金属热处理学报,1996,17( supply):104-108
14,李佐宜,彭子龙,郑远开等,金属颗粒薄膜巨磁电阻效应的影响因素,物理学报,1998,47(6)1012-1017
15,王长征,周宁,戎咏华等,金属颗粒膜巨磁电阻效应的机制和影响因素,功能材料,2003,3(34):238-241
16,王浩, 丁瑞钦, 杨恢东,高密度磁记录读写磁头用巨磁电阻薄膜研究进展,材料导报,1998,12(4):20-22
17,M. L. Yan, S. X. Li, C. T. Yu et al, Observation of giant magnetoresistance in Fe/Mo multilayers, J.Magn.Magn.Mater, 1995, 144: 539
18,J. Q. Xiao, S. J. Jiang et al. Giant magnetoresistance in nonmultilayer magnetic systems,Phys. Rev. Lett, 1992, 68: 3749
19,J. Q. Wang, G. Xiao, Finite-size effect and its temperature dependence of giant magnetoresistance in magnetic granular materials, Phys. Rev, 1994, B49(6):3982
20,蒋正生,张世远,都有为等,94 秋季中国材料研讨会论文集,北京,1994,2(1):227,231,254
21,S. A. Makhlonf, K. Sumiyama, K. Wakoh et al, Structural evolutions and magnetic properties of nano-granular metallic alloys, J.Appl.Phys, 1994, 33: 1323
22,K Sumiyama,K Suzuki,S. A Makhlouf et al.,Mater Sci Engineer,1995; B31:133
23 , Thangaraj, C NEcher, K. M. Krishman, Giant magnetoresistance and microstructural characteristics of epitaxial FeAg and CoAg granular thin films, J.Appl.Phys,1994,75(10):6900
24,Peng C.B.,Zhang S.,Li G.Z. et al.,J.Appl.Phys.,1994; 76(2):998
25,王浩,赵子强,钟运成,功能材料,1996; 27(5):449
26,王浩,赵子强,钟运成,材料科学与工程,1996; 14(4):14
27,Y. Ueda, T. Houga, H. Zaman et al, Magnetoresistance effect of Co-Cu nanostructure prepared by electrodeposition method, Journal of solid state chemistry, 1999, 147: 274-280
28,李浩华, 黎超, 李伟等,电沉积 Co-Cu 颗粒膜的巨磁电阻效应,物理化学学报,2000,16(6):573-574
29,R. Lopez Anton, M. L. Fdez-Gubieda, A. Garcia-Arribas, et al, Preparation and characterisation of Cu–Co heterogeneous alloys by potentiostatic electrodeposition, Materials Science and Engineering, 2002 (A335):94-100
30,R. Gyana, Pattanaik, K. Dinesh et al, Giant magnetoresistance and magnetic properties of electrodeposited Cu–Co granular films, Journal of Alloys and Compounds, 2001, 326: 260–264
31,S. Kainuma, K. Takayanagi, K. Hisatake, et al, Giant magnetoresistance and particle size distribution in pulse-plated Co-Cu granular .films, Journal of Magnetism and Magnetic Materials, 2002, 246 :207–212
32,姚素薇,赵瑾,王宏智,董大为,超晶格多层膜的电化学制备、表征及其GMR 特性的研究,物理化学学报,2003,19(10):892-895
33,姚素薇,赵瑾,张卫国,董大为,单晶硅上电沉积 Cu/Co 纳米多层膜及其巨磁电阻效应,化工学报,2004,55(3):414-417
34,赵瑾,电沉积 Cu/Co 纳米金属多层膜及其巨磁电阻性能的研究:[硕士学位论文],天津; 天津大学,2003
35,Yukimi Jyok, Satoshi Kashiwabara, Yasunori Hayashi, Preparation of Giant Magnetoresistance Co/Cu Multilayers by Electrodeposition, J.Electrochem.Soc, 1997,144(1):5-8
36,刘冰,半导体硅上液相沉积金属膜层的研究:[博士学位论文],天津; 天津大学,1997
37,A Yamada, T Houga, K Ueda, Magnetism and Magnetoresistance of Co/Cu Multilayer films produced by pulse control Electrodeposition Method, J. Magn. Magn. Mater, 2002, 239: 272-275
38,别青山,游彪,鹿牧等. 制备条件和退火对多层膜的巨磁电阻及结构的影响.南 京大学学报,1997,33(4):509-516
39,苏润,刘凤琴,钱海杰等. Co/Cu(111)薄膜生长和退火过程中的扩散.物理学报,2002,51(10):2327
40,卢正启.自旋阀巨磁电阻效应及其应用.物理[J],1998,(27):373
41,M. EI Harfaoui, H. Le Gall, J. Ben Youssef et al, GMR versus interfacial roughness induced from different buffers in (Co/Cu) ML, Journal of Magnetism and Magnetic Materials, 1999, 198-199 : 107-109
42,潘强, 沈鸿烈, 李铁等. Fe 为过渡层的 Co/Cu/Co 三明治巨磁电阻效应的研究.功能材料,2001, 32(2): 139-141
43,D. Schmool, A. Garcia-Arribas, E. Abad et al, Magnetic and structural changes in Cu90Co10 during the annealing process, Journal of Magnetism and Magnetic Materials, 1999, 203 : 73-75
44,T. A. Tochitskii, G. A. Jones, H. J. Blythe, et al, Fine structure and possible growth mechanisms of some electrodeposited CuCo granular films, Journal of Magnetism and Magnetic Materials, 2001, 224: 221-232
45,H. Errahmani, A. Berrada, G. Schmerber, et al, Magnetic and transport properties of ion beam sputtered CoxCu1~x granular alloys, Vacuum, 2000, 56: 221-226
46,G..Y. Yang, Jing Zhu, W.D. Wang, et al, Precipitation of nanoscale Co particles in granular Cu–Co alloy with giant magnetoresistance, Materials Research Bulletin 2000, 35: 875–885
47,T. A. Tochitskii, G. A. Jones, H. J. Blythe, et al, Fine structure and possible growth mechanisms of some electrodeposited CuCo granular films, Journal of Magnetism and Magnetic Materials, 2001, 224: 221-232
48,K. Miyazaki, S. Kainuma, K. Hisatake. et al, Giant magnetoresistance in Co-Cu granular alloy films and nanowires prepared by pulsed-electrodeposition, Electrochimica Acta, 1999, 44: 3713-3719
49,Shi-Hui Ge , Ying-Yang Lu, Zong-Zhi Zhang, et al, Giant magnetoresistance and microstructure of Co-Cu and FeCo-Cu granular films, Journal of Magnetism and Magnetic Materials, 1997, 168: 35-42
50,A. D. C. Viegas, J. Geshev, L. S. Dorneles, et al, Correlation between magnetic interactions and giant magnetoresistance in melt-spun Co10Cu90 granular alloys, Journal of Applied physics, 1997, 82(6): 3047
51,M. Kuzminski , A. Slawska-Waniewska, H.K. Lachowicz, et al, The effect of particle size and surface-to-volume ratio distribution on giant magnetoresistance (GMR) in melt-spun Cu-Co alloys, Journal of Magnetism and Magnetic Materials, 1999, 205: 7-13
2,刘吉平,郝向阳,纳米科学与技术,北京:科学出版社,2002:134-143
3,曹茂盛,关长斌,徐甲强,纳米材料导论,哈尔滨:哈尔滨工业大学出版社,2001:51
4,陈志军,王皓,傅正义,巨磁电阻材料研究进展,材料导报,2001,15(12):22
5,都有为, 纳米微粒系统中的巨磁电阻效应,物理,1997,26(10):627 –630
6,王宝军,颗粒膜的巨磁电阻效应,凉山大学学报,2003,5(2):18-21
7,都有为,磁性颗粒膜研究概况,金属功能材料,1995,4(5):122-124
8,M. N.Baibich,J.M.Brato, A.Fert, et al, Giant Magnetoresistance of (001)Fe/(001)Cr Magnetic Superlattices, Phys Rev.Lett, 1988, 61: 2472
9 , A.E.Berkowitz, J.R.Mitchell, M.J.Carey, et al, Giant magnetoresistance in heterogenous Cu-Co alloys, Phys.Rev.Lett, 1992, 68: 3749
10,J.Q.Xiao, J.S.Jieng, and C.L.Chien, Perpendicular magnetic anisotropy of Co–Ag granular thin films, Phys Rev Lett, 1992, 61: 1855
11,谢秉川,颗粒膜中的巨磁阻效应,广西师院学报,1999,16(4):27-32
12,都有为,纳米材料中的巨磁电阻效应,物理学进展,1997,17(2):180-181
13,张寿柏,蔡炳初,杨春生等,Co-Cu 合金颗粒膜的室温磁电阻效应,金属热处理学报,1996,17( supply):104-108
14,李佐宜,彭子龙,郑远开等,金属颗粒薄膜巨磁电阻效应的影响因素,物理学报,1998,47(6)1012-1017
15,王长征,周宁,戎咏华等,金属颗粒膜巨磁电阻效应的机制和影响因素,功能材料,2003,3(34):238-241
16,王浩, 丁瑞钦, 杨恢东,高密度磁记录读写磁头用巨磁电阻薄膜研究进展,材料导报,1998,12(4):20-22
17,M. L. Yan, S. X. Li, C. T. Yu et al, Observation of giant magnetoresistance in Fe/Mo multilayers, J.Magn.Magn.Mater, 1995, 144: 539
18,J. Q. Xiao, S. J. Jiang et al. Giant magnetoresistance in nonmultilayer magnetic systems,Phys. Rev. Lett, 1992, 68: 3749
19,J. Q. Wang, G. Xiao, Finite-size effect and its temperature dependence of giant magnetoresistance in magnetic granular materials, Phys. Rev, 1994, B49(6):3982
20,蒋正生,张世远,都有为等,94 秋季中国材料研讨会论文集,北京,1994,2(1):227,231,254
21,S. A. Makhlonf, K. Sumiyama, K. Wakoh et al, Structural evolutions and magnetic properties of nano-granular metallic alloys, J.Appl.Phys, 1994, 33: 1323
22,K Sumiyama,K Suzuki,S. A Makhlouf et al.,Mater Sci Engineer,1995; B31:133
23 , Thangaraj, C NEcher, K. M. Krishman, Giant magnetoresistance and microstructural characteristics of epitaxial FeAg and CoAg granular thin films, J.Appl.Phys,1994,75(10):6900
24,Peng C.B.,Zhang S.,Li G.Z. et al.,J.Appl.Phys.,1994; 76(2):998
25,王浩,赵子强,钟运成,功能材料,1996; 27(5):449
26,王浩,赵子强,钟运成,材料科学与工程,1996; 14(4):14
27,Y. Ueda, T. Houga, H. Zaman et al, Magnetoresistance effect of Co-Cu nanostructure prepared by electrodeposition method, Journal of solid state chemistry, 1999, 147: 274-280
28,李浩华, 黎超, 李伟等,电沉积 Co-Cu 颗粒膜的巨磁电阻效应,物理化学学报,2000,16(6):573-574
29,R. Lopez Anton, M. L. Fdez-Gubieda, A. Garcia-Arribas, et al, Preparation and characterisation of Cu–Co heterogeneous alloys by potentiostatic electrodeposition, Materials Science and Engineering, 2002 (A335):94-100
30,R. Gyana, Pattanaik, K. Dinesh et al, Giant magnetoresistance and magnetic properties of electrodeposited Cu–Co granular films, Journal of Alloys and Compounds, 2001, 326: 260–264
31,S. Kainuma, K. Takayanagi, K. Hisatake, et al, Giant magnetoresistance and particle size distribution in pulse-plated Co-Cu granular .films, Journal of Magnetism and Magnetic Materials, 2002, 246 :207–212
32,姚素薇,赵瑾,王宏智,董大为,超晶格多层膜的电化学制备、表征及其GMR 特性的研究,物理化学学报,2003,19(10):892-895
33,姚素薇,赵瑾,张卫国,董大为,单晶硅上电沉积 Cu/Co 纳米多层膜及其巨磁电阻效应,化工学报,2004,55(3):414-417
34,赵瑾,电沉积 Cu/Co 纳米金属多层膜及其巨磁电阻性能的研究:[硕士学位论文],天津; 天津大学,2003
35,Yukimi Jyok, Satoshi Kashiwabara, Yasunori Hayashi, Preparation of Giant Magnetoresistance Co/Cu Multilayers by Electrodeposition, J.Electrochem.Soc, 1997,144(1):5-8
36,刘冰,半导体硅上液相沉积金属膜层的研究:[博士学位论文],天津; 天津大学,1997
37,A Yamada, T Houga, K Ueda, Magnetism and Magnetoresistance of Co/Cu Multilayer films produced by pulse control Electrodeposition Method, J. Magn. Magn. Mater, 2002, 239: 272-275
38,别青山,游彪,鹿牧等. 制备条件和退火对多层膜的巨磁电阻及结构的影响.南 京大学学报,1997,33(4):509-516
39,苏润,刘凤琴,钱海杰等. Co/Cu(111)薄膜生长和退火过程中的扩散.物理学报,2002,51(10):2327
40,卢正启.自旋阀巨磁电阻效应及其应用.物理[J],1998,(27):373
41,M. EI Harfaoui, H. Le Gall, J. Ben Youssef et al, GMR versus interfacial roughness induced from different buffers in (Co/Cu) ML, Journal of Magnetism and Magnetic Materials, 1999, 198-199 : 107-109
42,潘强, 沈鸿烈, 李铁等. Fe 为过渡层的 Co/Cu/Co 三明治巨磁电阻效应的研究.功能材料,2001, 32(2): 139-141
43,D. Schmool, A. Garcia-Arribas, E. Abad et al, Magnetic and structural changes in Cu90Co10 during the annealing process, Journal of Magnetism and Magnetic Materials, 1999, 203 : 73-75
44,T. A. Tochitskii, G. A. Jones, H. J. Blythe, et al, Fine structure and possible growth mechanisms of some electrodeposited CuCo granular films, Journal of Magnetism and Magnetic Materials, 2001, 224: 221-232
45,H. Errahmani, A. Berrada, G. Schmerber, et al, Magnetic and transport properties of ion beam sputtered CoxCu1~x granular alloys, Vacuum, 2000, 56: 221-226
46,G..Y. Yang, Jing Zhu, W.D. Wang, et al, Precipitation of nanoscale Co particles in granular Cu–Co alloy with giant magnetoresistance, Materials Research Bulletin 2000, 35: 875–885
47,T. A. Tochitskii, G. A. Jones, H. J. Blythe, et al, Fine structure and possible growth mechanisms of some electrodeposited CuCo granular films, Journal of Magnetism and Magnetic Materials, 2001, 224: 221-232
48,K. Miyazaki, S. Kainuma, K. Hisatake. et al, Giant magnetoresistance in Co-Cu granular alloy films and nanowires prepared by pulsed-electrodeposition, Electrochimica Acta, 1999, 44: 3713-3719
49,Shi-Hui Ge , Ying-Yang Lu, Zong-Zhi Zhang, et al, Giant magnetoresistance and microstructure of Co-Cu and FeCo-Cu granular films, Journal of Magnetism and Magnetic Materials, 1997, 168: 35-42
50,A. D. C. Viegas, J. Geshev, L. S. Dorneles, et al, Correlation between magnetic interactions and giant magnetoresistance in melt-spun Co10Cu90 granular alloys, Journal of Applied physics, 1997, 82(6): 3047
51,M. Kuzminski , A. Slawska-Waniewska, H.K. Lachowicz, et al, The effect of particle size and surface-to-volume ratio distribution on giant magnetoresistance (GMR) in melt-spun Cu-Co alloys, Journal of Magnetism and Magnetic Materials, 1999, 205: 7-13