2009 年度研究工作进展

(1) 多种铁磁性纳米管的合成、结构和磁性研究

近年来M02课题组利用电化学沉积方法制备出了多种铁磁性的纳米线和纳米管，如：Fe、Co、Ni 单质以及它们的合金NiFe、CoFe、CoFeB和CoCrPt等。并系统地研究了它们的形貌、结构和各种磁学性质。研究发现，它们的磁学性质强烈地依赖于铁磁性纳米管的成分和各种几何参数。随着测量磁场角度的增加，它们的磁化反转机制会从“卷曲转动”变成“一致转动”。这些结果对于理解纳米尺度下的基本磁学性质，以及对于将来研究低维纳米尺度的器件都有重要的指导意义，特别是利用电化学方法制备可控的磁性层状纳米管，有可能开发出一种制备纳米环状自旋阀和磁性隧道结存储单元的低成本和高效率的新方法。有关近十种铁磁性纳米线和纳米管材料研究结果，2009年发表在先进材料杂志上[Adv. Mater. 21 (2009) 4619]。

(2) 具有线性磁场响应的磁性隧道结材料的制备与研究

基于TMR磁性隧道结材料和GMR巨磁电阻多层膜材料的磁敏传感器件要求其核心的部分具有线性的磁场响应。对外磁场响应的线性度一直是该领域的一个难点问题。2009年，我们制备了具有面内磁矩的CoFeB和垂直于平面磁矩的CoPt多层膜的Al-O势垒磁性隧道结材料，在垂直于平面的外磁场下，获得了22%室温磁电阻比值。磁电阻曲线具有对垂直于面内的磁场良好的线性响应，同时非线性度优于0.5%，非常适合高灵敏磁性传感器件的开发和应用。该项研究成果2009年发表[APL 94 (2009) 172902]。

2009 年会议论文目录

国际会议邀请报告：

[1] Inserted ultrathin Co, Cr and Mg layers effect at the two Fe/MgO interfaces in single crystal Fe/MgO/Fe magnetic tunnel junctions，J. Zhang, Y. Wang, X.G. Zhang and X. F. Han*，Second French-Chinese Workshopon Quantum Information and Spintronics withSemiconductors, 2009.10.11-16,Toulouse-Grenoble-Paris, France.

[2] Nanoring MTJ and its application in nanoring MRAM, X. F. Han*，Pakistan Institute of Physics International Conference 2009, 2009.2.23-26, Lahore, Pakistan

[3] Study on manufacturable nanoring-MRAM technology with current switching，X. F. Han*, ISTC/CSTIC 2009, ISTC (International Semiconductor Technology Conference) and CSTIC (China Semiconductor Technology International Conference)，2009.3.19-20，Shanghai, China

[4] Spin-dependent transport properties in single crystal Fe/MgO/Fe magnetic tunnel junctions by inserted ultrathin Co, Cr and Mg layers，Jia Zhang, Yan Wang, X.G. Zhang and X. F. Han*，The 2nd Photonics and OptoElectronics Meetings (POEM 2009), 2009.8.8-10，Wuhan, China.

[5] Nanoring Magnetic Tunnel Junction and its applications on nanoring MRAM, X. F. Han*，The German-China Bi-lateral Forum on Frontier of Nanotechnology and Nanostandardization, 2009.9.4-8, Lanzhou, China

[6] Spin-dependent transport properties in single crystal Fe/MgO/Fe- magnetic tunnel junctions by inserting ultrathin Co and Cr layers，J. Zhang, Y. Wang, X.G. Zhang and X. F. Han*，The Fifth Taiwan International Conference on Spintronics (TICSpin), 2009.9.9-11, Taichung City.

国际会议报告：

[1]Fabrication and magnetization reversal processes for Co/Cu multilayer nanowires，R. Sharif*, X. Q. Zhang, M. K. Rahman, S. Shamaila, J. Y. Chen, X. F. Han, and Y. K. Kim，International Magnetics Conference (Intermag 2009), 2009.4.5-8, Sacramento California, US.

[2] Spin-dependent transport properties in Langmuir-Blodgett-molecular barrier-based MTJs，D. P. Liu*，X. F. Han, Y. B. Hu and H. Guo，International Magnetics Conference (Intermag 2009), 2009.5.4-8，Sacramento California, US.

国内会议邀请报告：

[1] Patterned nano-ring magnetic tunnel junctions and nano-ring MRAM demo devices , X. F. Han, The 1st Chinese-French Workshop on Quantum Manipulation of Spins in Semiconductors , Oct.15-19 , 2007, Beijing, China

[2] Design and fabrication of nano-ring MRAM demo devices based on spin-polarized current driving , X. F. Han, China National Conference on Functional Materials and Applications , Nov.15-19, 2007, Wuhan , China

[3] Nanoring magnetic tunnel junctions and nanoring MRAM demo devices , X. F. Han, The 11th Chinese Conference of Low Temperature Physics , Aug.10-14 , 2007 , Haerbin , China

2009 年发表学术论文目录

[1]Structural and magnetic properties of various ferromagnetic nanotubes，X. F. Han，S. Shamaila, R. Sharif，J. Y. Chen，H. R. Liu，and D. P. Liu，Adv. Mater. 10 (2009) 4619

[2]Magnetic tunnel junction sensor with Co/Pt perpendicular anisotropy ferromagnetic layer，H. X. Wei, Q. H. Qin, Z. C. Wen, X. F. Han, and X. G. Zhang，Applied Physics Letters，94 (2009) 172902

[3]Electrochemical fabrication and magnetization properties of CoCrPt nanowires and nanotubes，S. Shamaila, D. P. Liu, R. Sharif, J. Y. Chen, H. R. Liu, and X. F. Han，Applied Physics Letters，94 (2009) 203101

[4]Magnetoresistance effect in antiferromagnet/nonmagnet/antiferromagnet multilayers，L.Wang,，S. G. Wang，S. Rizwan，Q. H. Qin，and X. F. Han，Applied Physics Letters，95 (2009) 15251

[5]Temperature dependence of resistance in epitaxial Fe/MgO/Fe magnetic tunnel junctions，Q. L.Ma，S. G. Wang, J. Zhang, Y. Wang, R. C. C. Ward, C. Wang, A. Kohn, X. G. Zhang, and X. F. Han，
Applied Physics Letters，95 (2009) 052506

[6]Room-temperature simultaneously enhanced magnetization and electric polarization in BiFeO3 ceramic synthesized by magnetic annealing,，W. J. Luo, D.L. Wang, F.W. Wang, T. Liu, J. W. Cai, L. Y. Zhang, and Y. L. Liu, Applied Physics Letters，94 (2009) 202507.

[7]Changes in the layer roughness and crystallography during the annealing of CoFeB/MgO/CoFeB magnetic tunnel junctions，G. I. R. Anderson, H. X. Wei, N. A. Porter, V. Harnchana, A. P. Brown, R. M. D. Brydson, D. A. Arena, J. Dvorak, X. F. Han, and C. H. Marrows，Journal of Applied Physics，105 (2009) 063904.

[8]Tunneling magnetoresistance in (Ga,Mn)As/Al–O/CoFeB hybrid structures，G. X. Du, M. R. Babu, X. F. Han, J. J. Deng, W. Z. Wang, J. H. Zhao, W. D. Wang, J. K. Tang，Journal of Applied Physics，105 (2009) 07C707.

[9]Composite metamaterials with dual-band magnetic resonances in the terahertz frequency regime，M. Li, Z. C. Wen, J. X. Fu, X. Fang, Y. M. Dai, and R. J. Liu，Journal of Applied Physics，42 (2009) 115420

[10]Characteristic length scale for spin polarized tunneling in Langmuir-Blodgett molecular magnetic tunnel junction，D. P. Liu, Y. B. Hu, H. Guo, and X. F. Han，IEEE Transaction on Magnetics，45 (2009) 10

[11]Structural and magnetic changes in MgO-based magnetic tunneling junctions，H. X. Wei, N. A. Porter, D. A. Arena, J. Dvorak, and X. F. Han，Journal of Magnetism and Magnetic Materials，Publish on line (2009)

[12]Bias voltage dependence of inverted magnetoresistance on the annealing temperature in MgO-based magnetic tunnel junctions，J. F. Feng, G. Feng, Q. L. Ma, X. F. Han, and J. M. D. Coey，Journal of Magnetism and Magnetic Materials，321 (2009) 3046

[13]Temperature dependence of inverted tunneling magnetoresistance in MgO-based magnetictunnel junctions，J. F. Feng, G. Feng, Q. L. Ma, X. F. Han, and J. M. D. Coey，Journal of Magnetism and Magnetic Materials，Publish on line (2009)

[14]Magnetic field annealing dependent magnetic properties of Co90Pt10 nanowire arrays，S. Shamailaa, R. Sharifa, J. Y. Chen, H. R. Liu, and X. F. Han，Journal of Magnetism and Magnetic Materials, 321 (2009) 3984

[15]Large perpendicular exchange bias in IrMn/CoFe/[Pt/Co] multilayers grown on a Ta/Pt buffer layer, Y. F. Liu, J. W. Cai, and S. L. He, Journal of Applied Physics D:Applied Physics，42 (2009)115002

[16]Electron spin resonance and AC susceptibility studies on La0.9Pb0.1MnO3 single crystals，M. R. Babu, X. F. Han, W. Ning, Z. H. Cheng, Y. Sun, and R. Jayavel，Materials Letters，63 (2009) 1528

[17]Structure, optical, and magnetic properties of rutile SnMnO thin films，Y. H. Xiao, S.H. Ge, L. Xi, Y.L. Zuo, X.Y. Zhou, L. Zhang, G.W. Wang, X. F. Han, Z.C. Wen，Applied Surface Science，255 (2009) 7981

[18]Dependence of interlayer AF coupling on ferromagnetic layer thickness in [Pt/Co]5/Ru/[Co/Pt]5 multilayers，J. Zhao, Y. J. Wang, and X. F. Han，Chinese Physics Letters,26 (2009) 037302

[19]Magnetization Reversal Mechanism for CoFeB Ferromagnetic Nanotube Arrays，H. R. Liu, S. Shamaila, J. Y. Chen, R. Sharif, Q. F. Lu and X. F. Han，Chinese Physics Letters,26 (2009) 077503

[20]Role of defects in magnetic properties of Fe-doped SnO2 film fabricated by the Sol-Gel method，X. Y. Zhou, S. H. Ge, X. F. Han, Y. L. Zuo, Y. H. Xiao, Z. C. Wen, L. Zhang, and M. J. Li，Chinese Physics B，18 (2009) 4025

[21]Progress on first-principles calculations and experimental results of single-crystalline magnetic tunnel junctions with MgO barriers (Invited review paper)，Y. Wang, J. Zhang, S. G. Wang, X. G. Zhang, and X. F. Han，Progress in Physics，29 (4) (2009) 375-392

国际合作与人员互访交流情况

国际合作课题

(1) 课题名称：磁性纳米结构中自旋相关隧穿的研究

合作单位：英国利兹大学

中方和外方项目负责人：韩秀峰研究员、Associate Prof. Christopher Marrows

　　项目来源： 国家基金委中英国际合作交流基金，2008-2009.

(2) 课题名称：基于 MgO 和Al-O 势垒磁性隧道结中自旋转移力矩效应的磁翻转研究

合作单位：日本东北大学应用物理系

中方和外方项目负责人：韩秀峰研究员、安藤康夫教授

项目来源：日本文部省和国家基金委JSPS-NSFC国际合作交流基金，2009—2011

国际合作与互访交流

2009 年由 M02 组负责主要接待工作的来访讲学和合作交流人员：

2009 年 M02 组派出合作交流人员 :

人才培养

2009 年研究生毕业论文