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by Lo Wai Hung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / by Lo Wai Hung. / Acknowledgements --- p.1 / Abstract / 論文摘要 --- p.ii / Table of Contents --- p.iv / List of Figures --- p.vi / List of Tables --- p.viii / Chapter Chapter 1. --- Introduction / Chapter 1.1. --- Magnetoresistance --- p.1 -1 / Chapter 1.1.1. --- Giant magnetoresistance (GMR) --- p.1 -2 / Chapter 1.1.2. --- Colossal Magnetoresistace (CMR) --- p.1 -2 / Chapter 1.2. --- Doping effects in La1-xCaxMn03 --- p.1-4 / Chapter 1.3. --- Metal-Insulator transition in CMR materials --- p.1 -8 / Chapter 1.3.1. --- The sharpness in Metal-Insulator transition --- p.1 -9 / Chapter 1.3.2. --- Possible model to explain CMR in rare-earth manganites --- p.1-12 / Chapter 1.4. --- Low field magnetoresistance --- p.1-14 / Chapter 1.4.1.1. --- Single crystal and polycrystalline perovskite manganites --- p.1-14 / Chapter 1.4.1.2. --- Manganite trilayer junctions --- p.1-15 / Chapter 1.4.2. --- Possible mechanism of low field MR --- p.1-16 / Chapter 1.5. --- Our motivation --- p.1-17 / Chapter 1.5.1. --- Brief review of several manganite superlattices systems --- p.1-18 / Chapter 1.5.2. --- Scope of this thesis work --- p.1-20 / References --- p.1-21 / Chapter Chapter 2. --- Epitaxial growth of LCMO thin films / Chapter 2.1. --- Deposition techniques --- p.2-1 / Chapter 2.1.1. --- Induction --- p.2-1 / Chapter 2.1.2. --- Facing-target sputtering (FTS) --- p.2-1 / Chapter 2.1.3. --- Vacuum system --- p.2-3 / Chapter 2.2. --- Fabrication and characterization of LCMO and PCMO targets --- p.2-4 / Chapter 2.3. --- Epitaxial growth of LCMO thin films --- p.2-9 / Chapter 2.3.1. --- Substrate materials --- p.2-9 / Chapter 2.3.2 --- Deposition --- p.2-10 / Chapter 2.3.2.1. --- Sample preparation --- p.2-10 / Chapter 2.3.2.2. --- Deposition procedure --- p.2-10 / Chapter 2.3.2.3. --- Inter-target distance --- p.2-11 / Chapter 2.3.2.4. --- Deposition Rate --- p.2-15 / Chapter 2.4. --- Substrate temperature effect --- p.2-17 / Chapter 2.4.1. --- Crystal Structure --- p.2-17 / Chapter 2.4.2. --- Transport properties --- p.2-20 / Chapter 2.4.2.1. --- Sharpness of M-I transport properties --- p.2-24 / Chapter 2.4.2.2. --- Magnetoresistance of LCMO/NGO films --- p.2-27 / Chapter 2.5. --- Thickness of LCMO thin film --- p.2-28 / Chapter 2.5.1. --- Crystal Structure --- p.2-29 / Chapter 2.5.2. --- M-I transition properties --- p.2-31 / Chapter 2.5.2.1. --- Sharpness of M-I transport properties --- p.2-35 / Chapter 2.5.2.2. --- Magnetoresistance of LCMO/NGO films --- p.2-36 / Chapter 2.5.2.3. --- Surface Morphology --- p.2-38 / Chapter 2.6. --- Epitaxial growth of PCMO thin films --- p.2-40 / Chapter 2.7. --- Conclusion --- p.2-42 / References --- p.2-43 / Chapter Chapter 3. --- LCMO/PCMO superlattices --- p.3-1 / Chapter 3.1. --- Variation of the PCMO thickness in LCMO/PCMO superlattices --- p.3-2 / Chapter 3.1.1. --- Sample Preparation --- p.3-2 / Chapter 3.1.2. --- Structure characterization by XRD --- p.3-3 / Chapter 3.1.3. --- Transport properties --- p.3-10 / Chapter 3.1.3.1. --- Sharpness of M-I transport properties --- p.3-14 / Chapter 3.1.3.2. --- Magnetoresistance of LCMO/PCMO superlattices --- p.3-16 / Chapter 3.2. --- Variation of the number of LCMO/PCMO bilayer --- p.3-19 / Chapter 3.2.1. --- Sample Preparation --- p.3-19 / Chapter 3.2.2. --- Structure characterization by XRD --- p.3-21 / Chapter 3.2.3. --- Transport properties --- p.3-23 / Chapter 3.2.3.1. --- Sharpness of M-I transport properties --- p.3-27 / Chapter 3.2.3.2. --- Magnetoresistance of LCMO/PCMO superlattices --- p.3-28 / Chapter 3.3. --- Fine adjusting the thickness of PCMO around 10Ain LCMO/PCMO superlattices / Chapter 3.3.1. --- Sample Preparation --- p.3-31 / Chapter 3.3.2. --- Characterization ofLCMO/PCMO superlattices by XRD --- p.3-32 / Chapter 3.3.3. --- Transport properties --- p.3-35 / Chapter 3.3.3.1. --- Sharpness of M-I transport properties --- p.3-39 / Chapter 3.3.3.2. --- Magnetoresistance of LCMO/PCMO superlattices --- p.3-41 / Chapter 3.4. --- Conclusion --- p.3-43 / References --- p.3-44 / Chapter Chapter 4. --- Low-field magnetoresistance (LFMR) / Chapter 4.1. --- Low-field magnetoresistance --- p.4-1 / Chapter 4.2. --- Conclusion --- p.4-5 / References --- p.4-6 / Chapter Chapter 5. --- Structure characterization of LCMO/PCMO superlatticess by crater edge profiling --- p.5-1 / Chapter 5.1. --- Sample preparation --- p.5-2 / Chapter 5.2. --- Structure Characterization --- p.5-2 / Chapter 5.2.1. --- X-ray diffraction (XRD) --- p.5-2 / Chapter 5.2.2. --- The crater edge profiling --- p.5-5 / Chapter 5.2.2.1. --- SEM --- p.5-5 / Chapter 5.2.2.2. --- AES line scan --- p.5-10 / Chapter 5.3. --- Crater edge profiling of P1OO/STO --- p.5-12 / Chapter 5.4. --- Conclusion --- p.5-15 / References --- p.5-16 / Chapter Chapter 6. --- Conclusion --- p.6-1

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FePt/B4C multilayer thin films are deposited on silicon substrates using magnetron sputtering with different B4C layer thickness. Experimental results suggest that the B4C layers effectively serve as spacers to separate the FePt layers, making the multilayer configuration stable even after film annealing at elevated temperatures. On the other hand, B and C are found to be incorporated into the FePt layer, which is responsible for the FePt grain growth confinement and grain separation, and eventually affects the properties of the composite film. Based on the experimental results of multilayer composite film, particle (FePt)/matrix (B4C) monolayer composite thin films on Si substrate are synthesized, in which a record coercivity of 2200 Oe is achieved compared to similar system. The size uniformity of the FePt nanoparticles, the well-defined particle-particle separation, together with the good magnetic property and high temperature thermal stability of the overall composite film, make it a very promising candidate for the ultrahigh density magnetic storage media. / Functional nanostructures serve as the basic building blocks for nanodevices and significant efforts have been devoted to their morphology control and properties optimization. In present study, four functional nanostructures, i.e., FePt/B4C multilayer composite film, particle (FePt)/matrix (B4C) monolayer composite film, Ga-doped ZnO nanowire arrays, and CdSe nanotube arrays are designed, synthesized and characterized in detail, in which the first two are expected to be prominent candidates for ultrahigh-density magnetic storage media while the later two have potential applications in solar energy conversion. / Semiconductor based one-dimensional nanostructures are investigated as promising building blocks for solar energy conversion devices. Two aspects are explored, aiming at increasing the energy conversion efficiency, i.e., facilitating electron transport and enhancing photon absorbing. In the first case, large area Ga-doped ZnO nanowire arrays are grown on transparent conducting substrate. Experimental results reveal the well-aligned array morphology and the uniform Ga concentration in these nanowires. In particular, direct I-V measurements performed on single nanowire-on-ITO substrate disclose its Ohmic contact with the conducting substrate and the significant conductivity improvement compared to undoped ZnO nanowire, In the second case, a novel synthesis strategy for nanotube arrays is developed and CdSe is used for demonstration, which material possessing more appropriate band gap as effective light harvester compared to that of materials for existing semiconductor nanotube arrays. The controllable tube wall thickness that can be increased until continuous CdSe porous network is obtained. The experimental results suggest a nanotube array formation mechanism that can be generally applied to a wide range of materials. / Zhou, Minjie = 功能纳米结构在磁性和能源方面的应用 / 周民杰. / Adviser: Li Quan. / Source: Dissertation Abstracts International, Volume: 72-11, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 91-100). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Zhou, Minjie = Gong neng na mi jie gou zai ci xing he neng yuan fang mian de ying yong / Zhou Minjie.