摘要
稀磁半导体(DMS)是实现自旋电子器件的材料基础。借助这种材料可以实现电子自旋的控制、输运和注入。尤其是最近发现的具有室温铁磁性的稀磁性氧化物体系，借助这种材料可以实现室温下的自旋过滤作用，使自旋电子器件的实用化成为可能，该方向也成为自旋电子学领域的研究热点。本文首先从材料设计理论入手，选择多种过渡族元素(V，Cr，Mn，Fe，Co，Ni)掺杂的宽禁带氧化物CeO_2体系为研究对象，使用WIEN2k软件包采用先进的LDA+U方法，通过对体系电子结构和态密度的计算，预测具有铁磁性的掺杂体系，并从理论上分析其铁磁性交换机制和起源问题，主要是氧空位对掺杂磁性离子耦合机制的影响及对体系铁磁性产生的贡献，首次从理论上发现：在掺杂CeO_2体系中磁性离子是通过氧空位产生的铁磁性耦合，符合氧空位诱导铁磁性交换耦合机制。在此理论的指导下，实验上采用平衡(固相烧结)和非平衡(磁控溅射，脉冲激光沉积-PLD)方法制备不同掺杂体系、不同浓度和共掺杂的CeO_2基稀磁氧化物薄膜和块材。制备过程中通过改变工艺条件、后处理退火等手段，对样品进行磁性能测试、微结构表征，辅助XPS和Raman光谱测试来研究对材料的室温铁磁性的影响。最终得到具有室温铁磁性的Ce_(0．97)Co_(0．03)O_(2-δ)块材和薄膜样品，其居里温度分别高达625K和760K。其室温铁磁性与氧空位浓度的关系在氧空位诱导铁磁性耦合机制下可以得到完美的解释，并通过共掺杂实验和Ar~+轰击方法对氧空位诱导铁磁性耦合机制进行了进一步实验验证。最后，采用四靶磁控溅射系统制备了具有不同中间层厚度的Ni(80nm)/Ce_(0．97)Co_(0．03)O_(2-δ)(d nm)/Co_(50)Fe_(50)(80nm)三层膜结构单元(d=1nm，3nm，5nm，10nm)，并通过磁阻(MR)测试在d=5nm的样品中得到室温下5％的磁电阻，从而证明了Ce_(0．97)Co_(0．03)O_(2-δ)材料的室温自旋过滤功能，展现出CeO_2基稀磁氧化物材料在自旋相关器件中巨大的应用前景。
Diluted magnetic semiconductor (DMS) is a key material for spintronics andrelated devices.Via this type of functional materials,the spins of electrons can beutilized,as the spin transportation and spin injection would be realized.Especially therecently developed diluted magnetic oxide,its high curier temperature (T_C) which iswell above room temperature,via which spin filtering-effect can be realized at roomtemperature,fundamentally facilitate the progress of spintronic-related devices onpractical aspect,and thus this field is being paid more and more attentions.Firstly,based on first principle calculations,several transitional elements (such as V,Cr,Mn,Fe,Co,Ni) doped CeO_2 systems are investigated with LDA+U methods in WIEN2kpackage.By calculating the electronic structure and density of state,the doped systemswith ferromagnetism (FM) are predicted,and the exchange coupling mechanism amongthe doped magnetic ions are further investigated,mainly focusing on the oxygenvacancy (V_O) related ferromagnetic exchange coupling mechanism.It is found thatmagnetic ions forms ferromagnetic coupling via Vo,which is well consistent withVo-induced ferromagnetic exchange coupling mechanism.And then from experimentalaspects,doped CeO_2 bulk and thin films with different elements and varied dopingcontents are synthesized by equilibrium methods (including solid-state reaction) andnon-equilibrium methods (including magnetron sputtering,pulsed laser deposition-PLD,and E-beam evaporation).With varied technology parameters and adopted postannealing,magnetic properties,micro-morphologies,as well as X-ray photoelectronspectroscopy (XPS) and Raman spctra of different samples are measured,to investigatethe influential factors for room temperature (RT)- FM.It is found experimentally thatthe FM is best for samples with the stoichiometry of Ce_(0.97)Co_(0.03)O_(2-δ),with a highestCurier temperature of 625K and 760K for its bulk and thin films,respectively.The V_Orelated FM can be well explained by Vo-induced ferromagnetic coupling mechanism,and further experiments of co-doping and Ar~+-bombardment methods are carried out forfurther investigation.At last,a three layered- structure of Ni(80nm)/Ce_(0.97)Co_(0.03)O_(2-δ)(dnm)/Co_(50)Fe_(50)(80nm) with viaried thickness of the inter layer (d=1,3,5,10 nm, respectively) are fabricated via four-targes magnetron sputtering system.Magneticresistance measurements indicate a 5% MR value in the sample with d=5nm thickness.This results provide a provement of the RT-spin filtering effect of Ce_(0.97)Co_(0.03)O_(2-δ) thinfilms,exhibiting a wide potential applications in spin-related devices.
引文
[1]H.Ohno.Making nonmagnetic semiconductors ferromagnetic.Science,1998,281:951-956
[2]S.A Wolf.,D.D.Awschalom,R.A.Buhrman,et al.Spintronics:a spin-based electronics vision for the future.Science,2001,294:1488-1495
[3]T.Fukumrua,Z.W.Jin,A.Ohtomo,et al.An oxide-diluted magnetic semiconductor:Mn-doped ZnO.Appllied Physics Letters,1999,75:3366-3368
[4]P.Sharma,A.Gupta,K.V.Rao,et al.Ferromagnetism above room temperature in bulk and transparent thin films of Mn-doped ZnO.Nature Materials,2003,2:673-677
[5]M.W.Wu,M.Q.Weng,J.L.Cheng.Spin dynamics in semiconductor nanostructures,in Physics,Chemistry and Application of Nanostructures:Reviews and short notes to nanomeeting 2007.Singapore.World Scientific,2007
[6]匡安龙，刘兴忡，路忠林，等．稀释磁性半导体Sn_(1-x)Mn_xO_2的室温铁磁性．物理学报，2005，54(6)：2934-2937
[7]S.J.Hu,S.S.Yan,X.L.Lin,et al.Electronic structure of Fe-doped In_2O_3 magnetic semiconductor with oxygen vacancies:Evidence for F-center mediated exchange interaction.Applied Physics Letters,2007,91:262514(1-3)
[8]S.S.Yan,J.P.Liu,L.M.Mei,et al.Spin-dependent variable range hopping and magnetoresistance in Ti_(1-x)Co_xO_2 and Zn_(1-x)Co_xO magnetic semiconductor films.Journal of Physics:Condensed Matter,2006,18:10469-10480
[9]S.J.Hu,S.S.Yan,M.W.Zhao,et al.First-principles LDA+U calculations of the Co-doped ZnO magnetic semiconductor.Physical Review B,2006,73:245205-245211
[10]J.K.Furdyna.Diluted magnetic semiconductors.Journal of Applied Physics,1988, 64:R29-R64
[11]H.Munekata,H.S.Ohno,von Moln(?)r,et al.Diluted magnetic Ⅲ-Ⅴ semiconductors.Physical Review letters,1989,63:1849-1852
[12]Ohno H.,Munekata H.,T.Penney,et al.Magnetotransport properties of p-type(In,Mn)As diluted magnetic Ⅲ-Ⅴ semiconductors.Physical Review letters,1992,68:2664-2667
[13]H.Ohno,A.Shen,F.Matsukura,et al.(Ga,Mn)As:A new diluted magnetic semiconductor based on GaAs.Applied Physics Letters,1996,69:363-365
[14] G A. Prinz. Magnetoelectronics. Science, 1998,282:1660-1663
[15] T. See Dietl, H. Ohno, F. Matsukura, et al. Zener model description of ferromagnetism in zinc-blende magnetic semiconductors. Science, 2000,287:1019-1022
[16] M. E. Overberg, C. R. Abernathy, and S. J. Peartonet, et al. Indication of ferromagnetism in molecular-beam-epitaxy-derived N-type GaMnN. Applied Physics Letters, 2001, 79:1312-1314
[17] M. L. Reed, N. A. EI-Masry, H. H. Stadelmaier, et al. Room temperature ferromagnetic properties of (Ga, Mn)N. Applied Physics Letters, 2001, 79:3473-3475
[18] K. Ando. Magneto-optical studies of s, p-d exchange interactions in GaN:Mn with room-temperature ferromagnetism. Applied Physics Letters, 2003, 82:100-102
[19] H. Saito, K. Ando. Room-temperature ferromagnetism in a Ⅱ-Ⅵ diluted magnetic semiconductor Zn_(1-x)Cr_xTe. Physical Review letters, 2003, 90:207202-207205
[20] W. Prellier, A. Fouchet, and B. Mercey. Oxide-diluted magnetic semiconductors: a review of the experimental status. Journal of Physics: Condensed Matter, 2003, 15:R1583-R1601
[21] S. J. Pearton, W. H. Heo, M. Ivill, et al. Dilute magnetic semiconducting oxides. Semiconductor Science and Technology, 2004, 19:R59-R74
[22] R. Janisch, P. Gopal, and N. A. Spaldin. Transition metal-doped TiO~2 and ZnO- present status of the field. Journal of Physics-Condensed Matter, 2005, 17:R657-R689
[23] Y. Matsumoto, M. Murakami, T. Shono, et al. Room-temperature ferromagnetism in transparent transition metal-doped titanium dioxide. Science, 2001, 291:854-856
[24] D. S. Goldobin and Arkady Pikovsky. Synchronization and desynchronization of self-sustained oscillators by common noise. Physics. Review B, 2005, 71:045201 -045204
[25] Guanshi Qin, Shenghong Huang, Yan Feng, et al. Photodegradation and photocuring in the operation of a blue upconversion fiber laser. Journal of Applied Physics, 2005, 97:126108(1-3)
[26] S. J. Han, T. H. Jang, Y. B. Kim, et al. Magnetism in Mn-doped ZnO bulk samples prepared by solid state reaction. Applied Physics Letters, 2003, 83:920-922
[27] T. Fukumura, Y. Yamada, H. Toyosaki, et al. Exploration of oxide-based diluted magnetic semiconductors toward transparent spintronics. Applied Surface Science, 2004, 223:62-67
[28] M. Venkatesan, C. B. Fitzgerald, J. G. Lunney, al. Anisotropic Ferromagnetism in Substituted Zinc Oxide. Physical Review letters, 93:177206-177209
[29] H. J. Lee, S. Y. Jeong, Chae Ryong Cho, et al. Study of diluted magnetic semiconductor: Co-doped ZnO. Applied Physics Letters, 2002, 81:4020-4022
[30] A. C. Tuan, J. D. Bryan, A. B. Pakhomov, et al. Epitaxial growth and properties of cobalt-doped ZnO on α-Al_2O_3 single-crystal substrates. Physical Review B, 2004, 70:054424(1-9)
[31] T. Dietl, A. Haury, and Y. M. d'Aubign(?). Free carrier-induced ferromagnetism in structures of diluted magnetic semiconductors. Physical Review B, 1997, 55:R3347-R3350
[32] D. A. Schwartz, D. R. Gamelin. Reversible 300K ferromagnetic ordering in a diluted magnetic semiconductor. Advanced Materials, 2004, 16:2115-2119
[33] Long Peng, Huaiwu Zhang, Qiye Wen, et al. Origin of Room-temperature ferromagnetism for Cobalt-doped ZnO diluted Magnetic Semiconductor. Chinese Physics Letters 2008, 25:1438-1441
[34] S. W. Jung, S. J. An, G C. Yi, et al. Ferromagnetic properties of Zn_(1-x)Mn_xO epitaxial thin films. Applied Physics Letters, 2002, 80:4561-4563
[35] Y. M. Kim, M. Yoon, I. -W. Park, et al. Synthesis and magnetic properties of Zn_(1-x)Mn_xO films prepared by the sol-gel method. Solid State Communications, 2004, 129:175-178
[36] W. Prellier, A. Fouchet, B. Mercey, et al. Laser ablation of Co:ZnO films deposited from Zn and Co metal targets on (0001) Al_2O_3 substrates. 2003, Applied Physics Letters, 82:3490-3492
[37] S. Ramachandran, A. Tiwari and J. Narayan. Zn_(0.9)Co_(0.1)O-based diluted magnetic semiconducting thin films. Applied Physics Letters, 2004, 84:5255-5257
[38] H. J. Lee, S. Y. Jeong, C. R. Cho, et al. Study of diluted magnetic semiconductor: Co-doped ZnO. Applied Physics Letters, 2002, 81:4020-4022
[39] K. A. Griffin, A. B. Pakhomov, C. M. Wang, et al. Intrinsic ferromagnetism in insulating cobalt doped anatase TiO_2. Physical Review letters, 2005, 94:157204-157207
[40] N. H. Hong, J. Sakai, N. Poirot, et al. Laser ablated Ni-doped HfO_2 thin films: room temperature ferromagnets. Applied Physics Letters, 86:242505-242507
[41] N. H. Hong, N. Poirot, J. Sakai. Evidence for magnetism due to oxygen vacancies in Fe-doped HfO_2 thin films. Applied Physics Letters, 2006, 89:042503-042505
[42] S. B. Ogale, R. J. Choudhary, J. P. Buban, et al. High temperature ferromagnetism with a giant magnetic moment in transparent Co-doped SnO_(2-δ) Physical Review letters, 2003, 91:077205(1-4)
[43] M. Venkatesan, C. B. Fitzgerald, J. M. D. Coey. Thin films Unexpected magnetism in a dielectric oxide. Nature, 2004,430:630-630
[44] S. Sonoda, S. Shimizu, S. Sasaki, et al. Moleclar beam epitaxy of wurtzite (Ga,Mn)N films on sapphire (0001) showing the ferromagnetic behaviour at room temperature. Journal of Crystal Growth, 2002,237:1358-1362
[45] M. Hashimoto, Y. K. Zhou, M. Kanamura,et al. High-temperature (>400K) ferromagnetism in Ⅲ-Ⅴ based diluted magnetic semiconductor GaCrN grown by ECR molecular-beam epitaxy. Solid State Communications, 2002,122:37-39
[46] Stephen Y. Wu, H. X. Liu, Lin Gu, et al. Synthesis, Characterization and modeling of high-quality ferromagnetic Cr-doped AlN thin films. Applied Physics Letters, 2003, 82:3047-3049
[47] N. H. Hong, J. Sakai, and A. Hassini. Ferromagnetism at room temperature with a large magnetic moment in anatase V-doped TiO_2 thin films. Applied Physics Letters, 2004, 84:2602-2604
[48] S. R. Shinde, S. B. Ogale, S. Das Sarma, et al. Ferromagnetism in laser-deposited anatase Ti_(1-x)Co_xO_(2-δ) films. Physical Review B, 2003, 67:115211-115216
[49] Z. J. Wang, J. K. Tang, L. D. Tung, et al. Ferromagnetism and transport properties of Fe-doped reduced-rutile TiO_(2-δ) films. Journal of Applied Physics, 2003, 93:7870-7872
[50] J. M. D. Coey, A. P. Douvalis, C. B. Fitzgerald, et al. Ferromagnetism in Fe-doped SnO_2 thin films, Applied Physics Letters, 2004, 84:1332-1334
[51] H. Saeki, H. Tabata, and T. Kawai. Magnetic and electric properties of vanadium doped ZnO films. Solid State Communications, 2001, 120:439-443
[52] K. Ueda, H. Tabata, and T. Kawai. Magnetic and electric properties of transition-metal-doped ZnO films. Applied Physics Letters, 2001, 79:988-990
[53] P. V. Radovanovic, and D. R. Gamelin. High-temperature ferromagnetism in Ni~(2+)-doped ZnO aggregates prepared from colloidal diluted magnetic semiconductor quantum dots. Physical Review letterss, 2003, 91:157202
[54] S. N. Kale, Bingying Cheng, and Daozhong Zhang. Magnetism in cobalt-doped Cu_2O thin films with and without Al, V and Zn codopants. Applied Physics Letters, 2003, 83:2100-2102
[55] J. Philip, N. Theodoropolou, G. Berera, J. S. Moodera. High-temperature ferromagnetism in manganese-doped indium-tin oxide films. Applied Physics Letters, 2004, 85:777-779
[56] A. Tiwari, V. M. Bhosle, S. Ramachandran, et al. Ferromagnetism in Co doped CeO_2: Observation of a giant magnetic moment with a high Curie temperature. Applied Physics Letters, 2006, 88:142511(1-3)
[57]B.Vodungbo,Y.Zheng,F.Vidal,et al.Room temperature ferromagnetism of Co doped CeO_(2-δ) diluted magnetic oxide:effect of oxygen and anisotropy.Applied Physics Letters,2007, 90:062510(1-3)
[58]V.Fernandes,J.J.Klein,N.Mattoso,et al.Room temperature ferromagnetism in Co-doped CeO_2 films on Si(001).Physical Review B,2007,75:121304(R)(1-4)
[59]Lei Bi,Hyun-Suk Kim,Gerald F.Dionne,et al.Structural,magnetic,and magneto-optical properties of Co-doped CeO_(2-δ)films.Journal of Applied Physics,2008,103:07D 138(1-3)
[60]A.Thurber,K.M.Reddy,V.Shutthanandan,et al.Ferromagnetism in chemically synthesized CeO_2 nanoparticles by Ni doping.Physical Review B,2007,76:165206(1-8)
[61]宛德福，马兴隆．磁性物理学．北京：电子工业出版社，1999
[62]T.Story,R.R.Galazka,R.B.Frankela,et al.Carrier-concentration-induced ferromagnetism in PbSnMnTe.Physical Review Letters,1986,56:777-779
[63]C.Zener.Interaction between the d shells in the transition metals.Physical Review,1951, 81:440-444
[64]T.Dietl,H.Ohno,A.Shen,et al.Hole-mediated ferromagnetism in tetrahedrally coordinated semiconductors Physical Review B,2001,63:195205(1-21)
[65]K.Sato and H.Katayams.Material design for transparent ferromagnets with ZnO-based magnetic semiconductors.Japanese Journal of Applied Physics,2000,39:L555-L558
[66]H.Akai.Ferromagnetism and its stability in the diluted magnetic semiconductor(In,Mn)As.Physical Review Letters,1998,81:3002-3005.
[67]P.A.Wolff,R.N.Bhatt,and A.C.Durst.Polaron-polaron interactions in diluted magnetic semiconductors.Journal of Applied Physics,1996,79:5196-5198
[68]J.M.D.Coey,M.Venkatesan,C.B.Fitzgerald.Donor impurity band exchange in dilute ferromagnetic oxides.Nature Materials,2005,4:173-179
[69]A.Kaminski and S.Das Sarma.Polaron percolation in diluted magnetic semiconductors.Physical Review Letters,2002,88:247202(1-4)
[70]S.D.Sarma,E.H.Hwang and A.Kaminski.Temperature-dependent magnetization in diluted magnetic semiconductors.Physical Review B,2003,67:155201(1-16)
[71]Yungyel Tyu,Tae-seok Lee,Jorge A.Lubguban,et al,Next generation of oxide photonic devices:ZnO-based ultraviolet light emitting diodes,Applied Physics Letters,2006, 88:241108(1-3)
[72] Y. Chen, N. T. Tuan, Y. Segawa, et al. Stimulated emission and optieal gain in ZnO epilayers grown by plasma-assisted molecular-beam epitaxy with buffers. Applied Physics Letters, 2001,78:1469-1471
[73] S. L. King, J. G E. Gardeniers. Pulsed-laser deposited ZnO for device applications. Applied Surface Science, 96-98:811-814 [74] Z. K. Tang, G K. L. Wang, P. Yu, et al. Molecular crystals and liquid crystals science and technology, 1997, 18(2-4):355-362
[75] J. C. Slater. Wave functions in a periodic potential. Physical Review, 1937, 51:846-851
[76] J. C. Slater. Atomic Radii in Crystals. Journal of Chemical Physics, 1964,41:3199
[77] D. J. Singh and L. Nordstr(?)om. Planewaves, pesudopotentials, and the LAPW method. New York: Springer, 2006.
[78] P. Blaha K. Schwarz, G K. H. Madsen, et al. WIEN2k User's Guide, 2001.
[79] K. Terakura, T. Oguchi, A. R. Williams, et al. Band theory of insulating transition-metal monoxides: band-structure calculations. Physical Review B, 1984, 30:4734-4747
[80] G A. Sawatzky and J. W. Allen. Magnitude and origin of the band gap in NiO. Physical Review Letters, 1984, 53:2339-2342 [81] V. I. Anisimov, H. Zaanen, and O. K. Andersen. Band theory and Mott insulators: Hubbard U instead of Stoner I. Physical Review B, 1991,44:943-954
[82] V. I. Anisimov, M. A. Korotin, J. Zaanen, et al. Spin bags, polarons, and impurity potentials in La_(2-x)Sr_xCuO_4 from first principles. Physical Review Letters, 1992, 68:345-348
[83] Stefano Fabris, Stefano de Gironcoli, Stefano Baroni, et al. Taming multiple valency with density functional: A case study of defective ceria. Physical Review B, 2005, 71:041102(R)(1-4)
[84] N. V. Skorodumova, R. Ahuja, S. I. Simak, et al. Electronic, bonding, and optical properties of CeO_2 and Ce_2O_3 from first principles. Physical Review B, 2000, 64:115108(1-9)
[85] R. D. Shannon. Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallographica Section A, 1976, 32:751-767
[86] D. C. Look. Characterization of homoepitaxial p-type ZnO grown by molecular beam epitaxy. Applied Physics Letters, 2002, 81:1830-1832
[87] M. Joseph, H. Tabata, H. Saeki, et al. Fabrication of the low-resistive p-type ZnO by codoping method. Physica B, 2001, 302:140-148
[88]D.A.Andersson,S.I.Simak,N.V.Skorodumova,et al.Optimization of ionic conductivity in doped ceria.Proceedings of the National Academy of Sciences of The United States of America,2006,103:3518-3521
[89]K.Schwarz.Materials design of solid electrolytes.Proceedings of The National Academy of Sciences of The United States of America,2006,103:3497
[90]T.Hibino,K.Ushiki and Y.Kuwahara.Electrochemical oxygen pump using CeO_2-based solid electrolyte for NO_x detection independent of O_2 concentration.Solid State Ionics,1997, 93:309-314
[91]Stefano Fabris,Stefano de Gironcoli,and Stefano Baroni.Reply to“Comment on‘Taming multiple valency with density functionals:A case study of defective ceria’”.Physical Review B,2005,72:237102(1-2)
[92]E.Wuilloud,B.Delley,W.D.Schneider.Spectroscopic evidence for localized and extended f-symmetry states in CeO_2.Physical Review Letters,1984,53:202-205
[93]D.D.Koelling,A.M.Boring and J.H.Wood.The electronic structure of CeO_2 and PrO_2.Solid State Communications,1983,47:227-232
[94]G.Adachi and N.Imanaka.The Binary Rare Earth Oxides.Chemical Reviews,1998, 98:1479-1514
[95]J.M.Qiao,Cary Y.Yang.High-Tc superconductors on buffered silicon:materials properties and device applications.Materials Science and Engineering:Reports,1995,R14:157-202
[96]麦振洪．薄膜结构X射线表征．北京：科学出版社，2007
[97]T.A.Clarke,E.N.Rizkalla.X-ray photoelectron spectroscopy of some silicates.Chemical Physics Letters,1976,37:523-526
[98]A.Nakajima,A.Yoshihara,and M.Ishigame.Defect-induced raman spectra in doped CeO_2.Physical Review B,1994,50:297-307
[99]B.T.Kilbourn.Cerium,a guide to its role in chemical technology.Molycorp,NY,1992
[100]JCPDS-International Committee for Diffraction Data,Card #43-1002
[101]C.Wang,M.Xiao,W.Chen.Chemical Abstract Number,112:46676
[102]A.Thurber,K.M.Reddy,and A.Punnoose.High-temperature magnetic-field-induced activation of room temperature ferromagnetism in Ce_(1-x)Ni_xO_2.Journal of Applied Physics, 2007,101:09N506(1-3)
[103] T. Zhang, P. Hing, H. Huang. Densification, microstructure and grain growth in the CeO_2-Fe_2O_3 system (0≤Fe/Ce≤20%). Journal of the European Ceramic Society, 2001, 21:2221-2228
[104] I. Vinokurov, Z. Zonn, and V. Ioffe. I. Vinokurov, Z. Zonn, and V. Ioffe. Soviet physics, Solid state. New York: American Institute of Physics, 1968
[105] Y. B. Zhang, Q. Liu, T. Sritharan, et al. Characterization of homoepitaxial p-type ZnO grown by molecular beam epitaxy. Applied Physics Letters, 2006, 89:042510(1-3)
[106]C. Worledge, T. H. Geballe. Magnetoresistive double spin filter tunnel junction. Journal of Applied Physics, 2000, 88:5277-5279
[107] J. R. McBride, K. C. Hass, B. D. Poindexter, W. H. Weber, Journal of Applied Physics, 1994, 76:2435-2441
[108] Jonathan E. Spanier, Richard D. Robinson, Feng Zhang, et al. Size-dependent properties of CeO_(2-y) nanoparticles as studied by Raman scattering. Physical Review B, 2001, 64:245407(1-8)
[109] H. Yoshida, T. Inagakia, K. Miurac, et al. Density functional theory calculation on the effect of local structure of doped ceria on ionic conductivity. Solid State Ionics, 2003, 160:109-116
[110]C. Levy, C. Guizard, A. Julbe. Synthesis of ceria based ion conductiong mesoporous membranes by soft-chemistry. Separation and Purification Technology, 2003, 32:327-333
[111] D. Rajiv, V. L. Richards, X. P. Wang. Development of ceria-based electrolytes. Journal of the Electrochemical Society, 1998, 145:414-421
[112]C. S. Montross. Precipitation and bulk property behaviour in the yttria-magnesia-zirconia ternary system. British Ceramic Transactions, 1991, 90:175-178
[113] P. Gr(?)nberg, R. Schreiber, Y. Pang, et al. Layered-magnetic structures: evidence for antiferromagnetic coupling of Fe layers across Cr interlayers. Physical Review Letters, 1986, 57:2442-2445
[114]M. N. Baibich, J. M. Broto, A. Fert, et al. Giant Magnetoresistance of (001)Fe/(001)Cr magnetic superlattices. Physical Review Letters, 1988, 61:2472-2475
[115]B. Dieny, V. S. Speriosu, S. S. P. Parkin, et al. Giant magnetoresistive in soft ferromagnetic multilayers. Physical Review B, 1991, 43:1297-1300
[116]T. Miyazaki, T. Yaoi, and S. Ishio. Large magnetoresistance effect in 82Ni-Fe/Al-Al_2O_3/Co magnetic tunneling junction. Journal of Magnetism and Magnetic Materials, 1991, 109:L7-L9
[117]T.Miyazaki,N.Tezuka.Journal of Magnetism and Magnetic Materials,1995,139:L231-L234; Spin polarized tunneling in ferromagnet/insulator/ferromagnet junctions.1995,151:403-410
[118]T.Inoue,Y.Yamamoto,S.Koyama,et al.Epitaxial growth of CeO_2 layers on silicon.Applied Physics Letters,1990,56:1332-1333
[119]T.Chikyow,S.M.Bedair,L.Tye,et al.Reaction and regrowth control of CeO_2 on Si(111) surface for the silicon-on-insulator structure.Applied Physics Letters,1994,65:1030-1032
[120]Y.Wei,X.Hu,Y.Liang,et al.Mechanism of cleaning Si(001)surface using Sr or SrO for the growth of crystalline SrTiO_3 films.The Journal of Vacuum Science and Technology B,2002, 20:1402-1405
[121]I.M.Kotelyanskii,V.A.Luzanov,Yu.M.Dikaev,et al.Deposition of CeO_2 films including areas with the different orientation and sharp border between them.Thin Solid Films,1996, 280:163-166
[122]S.C.Speller.Thallium based high temperature superconductors for microwave device applications.Materials Science and technology,2003,19:269-282
[123]S.V.Sokolov,A.V.Knotko,V.I.Putlaykv,et al.Characterization of CeO_2 thin films on a sapphire.Superlattices and Microstructures,1998,24:49-53
[124]A.G.Zaitsev,Roger W(?)rdenweber,Georg Ockenfu,et al.Microwave losses and structural properties of large-area YBa_2Cu_3O_7 films on r-cut sapphire buffered with(001)/(111)oriented CeO_2.IEEE Transactions on Applied Superconductivity,7(1997),1482-1485
[125]熊杰，陶伯万，谢廷明，等．蓝宝石衬底上射频溅射法生长CeO_2外延薄膜研究．低温物理学报，2005(27)：234-240
[126]X.D.Wu,R.C.Dye,R.E.Muenchausen,et al.Epitaxial CeO_2 films as buffer layers for high-temperature superconducting thin films.1991,58:2165-2167
[127]T.Suzuki,I.Kosacki,V.Petrovsky,et al.Optical properties of undoped and Gd-doped CeO_2 nanocrystalline thin films.Journal of Applied Physics,2002,91:2308-2314
[128]P.F.Xing,Y.X.Chen,Shi-Shen Yan,et al.High temperature ferromagnetism and perpendicular magnetic anisotropy in Fe-doped In_2O_3 films.Applied Physics Letters,2008, 92:022513
[129]M.Venkatesan,C.B.Fitzgerald,J.G.Lunney,and J.M.D.Coey.Anisotropic ferromagnetism in substituted Zinc oxide.Physical Review Letters,2004,93:177206(1-4)
[130]Juan P.Holgado,Rafael Alvarez and Guillermo Munuera.Study of CeO_2 XPS spectra by factor analysis:reduction of CeO_2.Applied Surface Science,2000,161:301-307
[131]夏建白，葛惟昆，常凯．半导体自旋电子学．北京：科学出版社，2008
[132]P.Fumagalli,H.Munekata.Magneto-optic properties and ferromagnetism of(In,Mn)As/ (In,Al)As/(Ga,Al)Sb heterostructures.Physical Review B,1996,53:15045-15053
[133]J.Sinova,T.Jungwirth,J.Kucera,et al.Infrared magneto-optical properties of(Ⅲ,Mn)V ferromagetic semiconductors.Physical Review B,2003,67:235203(1-12)
[134]J.Carlos Egues.Spin-dependent perpendicular magnetotransport through a tunable ZnSe/Zn_(1-x)Mn_xSe heterostructure:a possible spin filter?.Physical Review Letters,1998, 80:4578-4581
[135]M.Oestreich,J.H(?)bner,D.H(?)gele,et al.Spin injection into semiconductors.Applied Physics Letters,1999,74:1251-1253
[136]N.F.Mott.The Resistance and Thermoelectric Properties of the Transition Metals.Proceedings of the Royal Society,1936,156:368-382;N.F.Mott.Electrons in transition metals.Advances in Physics,1964,13:325-422
[137]H.A.M.Van den Berg.Physics of and method for studying metallic multilayers with interlayer exchange coupling and GMR response.In:Hartmann U,eds.Magnetic Multilayers and Giant Magnetoresistance.Berlin:Springer,2000.211-216
[138]R.L.White.Giant magnetoresistance:a primer.IEEE Transactions on Magnetics.1992, 28:2482-2487
[139]B.Dieny,A.Vedyayev,N.Ryzhanova.Comparison of semiclassical and real-space quantum theories of giant magnetoresistance.Journal of Magnetism and Magnetic Materials,1993, 121:366-370
[140]R.Fiederling,M.Keim,G.Reuscher,et al.Electrical spin injection in a ferromagnetic semiconductor heterostructure.Nature,1999,402:790-792
[141]H.Ohno,D.Chiba,F.Matsukura,et al.Nature,2000,408:944-946
[142]M.Tanaka and Y.Higo.Large tunneling magnetoresistance in GaMnAs/AlAs/GaMnAs ferromagnetic semiconductor tunnel junctions.Physical Review Letters,2001,87:026602(1-4)
[143]G.Schmidt,D.Ferrand,L.W.Molenkamp,et al.Fundamental obstacle for electrical spin injection from a ferromagnetic metal into a diffusive semiconductor.Physical Review B,200, 62:R4790-R4793
[144]G.Schmidt and Laurens W.Molenkamp.Dilute magnetic semiconductors in spin-polarized electronics.Journal of Applied Physics,2001,89:7443-7447
[145]K. Kayanuma, T. Tomita, A. Murayama, et al. Optical study of spin injection dynamics in double quantum wells of Ⅱ-Ⅵ diluted magnetic semiconductors. AIP Conference Proceedings, 2005,772:1387-1388
[146] Clifford T. Tanaka, Janusz Nowak, and Jagadeesh S. Moodera. Spin-polarized tunneling in a half-metallic ferromagnet. Journal of Applied Physics, 1999, 86:6239-6242
[147] J. S. Moodera and G Mathon. Spin polarized tunnelin in ferromagnetic junctions. Journal of Magnetism and Magnetic Materials, 1999, 200:248-273; K. Inomata. Exchange-biased magnetic tunnel junctions and application to nonvolatile magnetic random access memory. Journal of the Magnetics Society of Japan, 1999,23:1826-1835
[148] R. Meservey and P. M. Tedrow. Spin-polarized electron tunneling. Physics Reports, 1994, 38:173-243
[149] J. S. Moodera, L. R. Kinder, T. M. Wong et al. Large magnetoresistance at room temperature in ferromagnetic thin film tunnel junctions. Physical Review Letters, 1995, 74:3273-3276
[150] J. S. Moodera, R. Meservey and X. Hao. Variation of the electron-spin polarization in EuSe tunnel junctions from zero to near 100% in a magnetic field. Physical Review Letters, 1993, 70:853-856
[151] E. I. Rashba. Theory of electrical spin injection: Tunnel contacts as a solution of the conductivity mismatch problem. Physical Review B, 2000, 62:R16267-R16270
[152] A. T. Hanbicki, B. T. Jonker, G Itskos, et al. Efficient electrical spin injection from a magnetic metal/tunnel barrier contact into a semiconductor. Applied Physics Letters, 80:1240-1242
[153] M. Covington, J. Nowak, and D. Song. Magnetic tunnel junction performance versus barrier thickness : NiFe/AlOx/NiFe Junctions fabricated from a wedged Al layer. Applied Physics Letters, 2000, 76:3965-3967
[154] J. G Simmons. Generalized formula for the electric tunnel effect between similar electrodes separated by a thin insulating films. Journal of Applied Physics, 1963, 34:1793-1803
[155] J. G Simmons. Electric tunnel effect between dissimilar electrodes separated by a thin insulating film. Journal of Applied Physics, 1963, 34:2581-2590
[156]白海力,姜恩勇.磁隧道结(MTJ).科学通报,2001, (46):92-99
