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Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The use of high voltage direct current (HVDC) applications has gained enormous popularity for long distance power transmission. This is due to the lucrative benefits offered by this type of power transmission technology when compared to the traditional high voltage alternative current (HVAC). This new shift in the paradigm of power system design has led to the increased interest in the research that focuses on issues relating to the reliability of power supply associated with HVDC. Amongst such issues, insulation coordination has increasingly become a challenging task that continues to receive renewed research focus. It has been convincingly demonstrated, both from field experience and laboratory research, that insulator contamination constitutes a multifaceted phenomenon, especially when transmission voltages ramp up into high operating voltage levels. More so, this is particularly interesting with reference to the increasing applications of high voltage direct current (HVDC). The recently commissioned HVDC power-line in Namibia is one of the major motivations upon which NamPower (Namibia‟s national power utility) has committed financial resources to research on insulator pollution performance. This project was a part of NamPower‟s research initiative – seeking to investigate the phenomena associated with insulator pollution performance under natural pollution environments when energized under both AC and DC excitation voltage types. The significance of this research is especially crucial for HVDC applications given the paucity of research conducted on the DC performance of insulators, under natural pollution environments. This study was conducted at the Koeberg Insulator Pollution Test Station (KIPTS) on the west coast of Cape Town in the Western Cape province of South Africa. KIPTS is an internationally recognized insulator pollution test facility, which is widely used by both insulator manufacturers and academic researchers from many parts of the world. STRI and ABB, both Swedish-based companies, are good examples of international subscribers to the KIPTS research facility. The first objective of this research was to design a suitable DC excitation voltage system for both DC+ and DC- to be used at KIPTS. This apparatus was designed and built at the University of Stellenbosch. The second objective was to conduct a comparative evaluation of the performance of high temperature vulcanized silicone rubber (HTV-SR) power line insulators under AC, DC+ and DC- when subjected to natural pollution conditions at KIPTS. All test insulators were made from the same material and sourced from the same manufacturer – having different creepage lengths. Five different creepage lengths were considered for each excitation voltage – summing up to fifteen HTV-SR test samples. A standard DC glass disc insulator was also installed on each excitation voltage as a control sample. It was therefore envisaged that this study would give rise to new research questions, leading to future explorations on the subject. With reference to weather monitoring and leakage current measurements (using an online leakage current monitoring device - OLCA), a correlation was found to exist between the variations in climatic conditions and the corresponding occurrence of leakage current on the insulator surfaces. High leakage current levels were recorded in summer due to the high pollution levels that were measured in that season (using the equivalent salt deposit density (ESDD) approach). Winter, in contrast, had lower levels of leakage current recorded. This corresponds to a high prevalence of rainfall in winter, which caused occasional natural washing of the insulator surfaces. The leakage current levels for the HTV-SR insulators were of a similar order of magnitude for AC and DC+ and lower for DC-. The harshest pollutants (with high conductivities, as measured with the directional dust deposit gauges (DDDG)) were found to have emanated largely from the south. As a result, most instances of erosion were observed in the southward direction on the test insulators. The electrical discharge activity observations, conducted at night, had revealed that dryband corona (DBC) and dryband discharge (DBD) prominently occurred on the terminating sheaths (both live and ground ends) and bottom side of HTV-SR and glass disc insulators, respectively. This justifies the dominance of erosion that was observed on the terminating sheaths and bottom side of HTV-SR and glass disc insulators, respectively. Flashover events were recorded on the shortest HTV-SR insulator installed on DC+ and the glass disc insulator installed on DC-. All flashover events occurred in summer (the harshest season at KIPTS). Two interesting observations, albeit unexplained, were observed: star-shaped erosion on the shed bottoms of the HTV-SR insulators installed on DC+ and material peel-off at the shed-to-sheath bonding interface of the HTV-SR insulators installed on DC-. These observations therefore require further investigation in order to establish possible explanations. / AFRIKAANSE OPSOMMING: Die gebruik van hoë gelykspanning (HSGS) het baie gewild geword vir kragtransmissie oor lang afstande. Dit is as gevolg van die uitstekende voordele wat hierdie tipe tegnologie teenoor die tradisionele hoë wisselspanning (HSWS) bied. Hierdie paradigmaskuif in die ontwerp van kragstelsels het tot verhoogde belangstelling in navorsing gelei wat betrekking het op aspekte wat verband hou met die betroubaarheid van kragvoorsiening deur HSGS. Van hierdie aspekte word isolasiekoördinasie toenemend ʼn uitdagende taak en navorsing word tans daarop toegespits. Daar bestaan oortuigende bewyse, gebaseer op laboratorium- en veldtoetse dat isolatorbesoedeling ʼn verskynsel met vele fasette is, veral wanneer hoër spannings gebruik word. Dit is in „n meerdere mate van belang met verwysing na toepassings van HSGS. Die onlangs inbedryfgestelde HSGS kraglyn in Namibië is een van die hoofmotiverings vir die verskaffing van geldelike steun deur NamPower (Namibië se nasionale kragvoorsiener) vir navorsing oor die besoedelingsprestasie van isolators. Hierdie projek is deel van NamPower se navorsingsinisiatief om verskynsels betreffende die besoedelingsprestasie van isolators in natuurlik-besoedelde omgewings te ondersoek, onder WS en GS-bekragtiging. Die betekenis van hierdie navorsing is veral belangrik vir die HSGS-toepassings in die lig van die skaarsheid van navorsing oor die GS-prestasie van isolators in natuurlik-besoedelde omgewings. Hierdie studie is gedoen by die Koeberg isolatorbesoedelingstoetsstasie (KIPTS) aan die weskus van die Wes-Kaap. KIPTS is 'n internasionaal-erkende toetsfasiliteit en word algemeen gebruik deur beide isolatorvervaardigers en akademiese navorsers uit baie dele van die wêreld. STRI en ABB, albei Sweeds-gebaseerde maatskappye, is die goeie voorbeelde van die internasionale gebruikers van die KIPTS navorsingsfasiliteit. Die oogmerk van hierdie navorsing was om eerstens 'n geskikte GS-kragbron vir beide die GS+ en die GS- vir gebruik by KIPTS te ontwerp. Hierdie apparaat is ontwerp en gebou deur die Universiteit van Stellenbosch. Tweedens is 'n vergelykende evaluering van die prestasie hoë temperatuur gevulkaniseerde silikoon (HTV-SR) kraglynisolators onder WS, GS+ en GS– onder natuurlike besoedeling by die KIPTS uitgevoer. Alle toetsisolators is van dieselfde materiaal gemaak en is afkomstig van dieselfde vervaardiger, maar het verskillende kruipafstande. Vyf verskillende kruipafstande is gebruik vir elke tipe spanning  'n totaal van vyftien HTV-SR toets monsters. 'n Standaard GS glasisolatorskyf is ook vir elke spanning as' n kontrolemonster geïnstalleer. Dit kan dus verwag word dat hierdie studie aanleiding sal gee tot nuwe navorsingsvrae, wat kan lei tot verdere toekomstige ondersoeke oor die onderwerp. Met verwysing na die monitering van die weer en die lekstroommetings (met behulp van 'n aanlyn-lekstroommoniteringstoestel - OLCA), is 'n korrelasie gevind tussen die variasie in klimaatstoestande en die ooreenstemmende voorkoms van lekstroom op die isolator- oppervlaktes. Hoë lekstroomvlakke is waargeneem in die somer, as gevolg van die hoë besoedelingsvlakke wat in daardie seisoen gemeet is (met behulp van die ekwivalente soutneerslag-digtheid (ESDD) metode). In die winter, in teenstelling, is die laagste vlakke van lekstroom aangeteken. Dit stem ooreen met 'n hoë voorkoms van reënval in die winter, wat die isolatoroppervlaktes van tyd tot tyd natuurlik gewas het. Die lekstroomvlakke op die HTV-SR isolators was van soortgelyke ordegrootte vir WS en GS+ maar laer vir GS-. Dit is bevind dat die ergste besoedelingstowwe, met 'n hoë geleiding, soos gemeet met die rigtingsensitiewe stofneerslagsmeters (DDDG), hoofsaaklik uit ʼn suidelike rigting kom. As gevolg hiervan, is die meeste gevalle van erosie aan die suidekant van die toetsisolators waargeneem. Die waarneming van elektriese ontladingsaktiwiteit in die nag, het aan die lig gebring dat droëbandkorona (DBC) en droëbandontladings (DBD) prominent voorgekom het op die skedes aan die uiteindes (beide lewende en grond kante) en onderste kant van HTV-SR en glasskywe, onderskeidelik. Oorvonkings is waargeneem op die kortste HTV-SR isolator op GS+ en op die glasisolator op GS-. Al die oorvonkings het in die somer (die ergste seisoen by KIPTS) voorgekom. Twee interessante, dog onverklaarbare, verskynsels is waargeneem: stervormige erosie aan die onderkante van die skerms van die HTV-SR isolators op GS+ en material-afskilfering by die skerm-skede tussenvlak van die HTV-SR isolators op GS-. Hierdie verskynsels vereis verdere ondersoek ten einde moontlike verklarings vas te stel.

Microelectronics has enjoyed great success in the past century. As the technology node progresses, the complementary metal-oxide-semiconductor scaling has already reached a wall, and serious challenges in high-bandwidth interconnects and fast-speed signal processing arise. The incorporation of photonics to microelectronics provides potential solutions. The theme of this thesis is focused on the novel applications of travelling-wave microresonators such as microdisks and microrings for the on-chip optical interconnects and signal processing. Challenges arising from these applications including theoretical and experimental ones are addressed. On the theoretical aspect, a modified version of coupled mode theory is offered for the TM-polarization in high index contrast material systems. Through numerical comparisons, it is shown that our modified coupled mode theory is more accurate than all the existing ones. The coupling-induced phase responses are also studied, which is of critical importance to coupled-resonator structures. Different coupling structures are studied by a customized numerical code, revealing that the phase response of symmetric couplers with the symmetry about the wave propagating direction can be simply estimated while the one of asymmetric couplers is more complicated. Mode splitting and scattering loss, which are two important features commonly observed in the spectrum of high-Q microresonators, are also investigated. Our review of the existing analytical approaches shows that they have only achieved partial success. Especially, different models have been proposed for several distinct regimes and cannot be reconciled. In this thesis, a unified approach is developed for the general case to achieve a complete understanding of these two effects. On the experimental aspect, we first develop a new fabrication recipe with a focus on the accurate dimensional control and low-loss performance. HSQ is employed as the electron-beam resist, and the lithography and plasma etching steps are both optimized to achieve vertical and smooth sidewalls. A third-order temperature-insensitive coupled-resonator filter is designed and demonstrated in the silicon-on-insulator (SOI) platform, which serves as a critical building block element in terabit/s on-chip networks. Two design challenges, i.e., a broadband flat-band response and a temperature-insensitive design, are coherently addressed by employing the redundant bandwidth of the filter channel caused by the dispersion as thermal guard band. As a result, the filter can accommodate 21 WDM channels with a data rate up to 100 gigabit/s per wavelength channel, while providing a sufficient thermal guard band to tolerate more than ±15°C temperature fluctuations in the on-chip environment. In this thesis, high-Q microdisk resonators are also proposed to be used as low-loss delay lines for narrowband filters. Pulley coupling scheme is used to selectively couple to one of the radial modes of the microdisk and also to achieve a strong coupling. A first-order tunable narrowband filter based on the microdisk-based delay line is experimentally demonstrated in an SOI platform, which shows a tunable bandwidth from 4.1 GHz to 0.47 GHz with an overall size of 0.05 mm². Finally, to address the challenges for the resonator-based delay lines encountered in the SOI platform, we propose to vertically integrate silicon nitride to the SOI platform, which can potentially have significantly lower propagation loss and higher power handling capability. High-Q silicon nitride microresonators are demonstrated; especially, microresonators with a 16 million intrinsic Q and a moderate size of 240 µm radius are realized, which is one order of magnitude improvement compared to what can be achieved in the SOI platform using the same fabrication technology. We have also successfully grown silicon nitride on top of SOI and a good coupling has been achieved between the silicon nitride and the silicon layers.

Contact electrification refers to the transfer of electrical charges between two surfaces, similar and dissimilar, as they are brought into contact and separated; this phenomenon is also known as static electrification or triboelectrification. For example, everyone has experienced weak electrical shocks from metal doorknobs, wool and synthetic clothing on dry days. While contact electrification might appear insignificant, it plays a key role in numerous natural and industrial processes, including atmospheric lightning, accumulation of dust on solar panels, charging of liquids during pipetting and flow in the tubes, and fire hazards in granular media. Contact electrification at metal-metal interfaces is well understood in terms of transfer of electrons, but a comprehensive understanding of contact electrification at interfaces of electrical insulators, such as air, water, polytetrafluoroethylene (PTFE), polypropylene remains incomplete. In fact, a variety of mechanisms responsible for transfer of electrical charges during mechanical rubbing, slipping, sliding, or flow at interfaces have been proposed via: electrons, ions, protons, hydroxide ions from water, specific orientation of dipoles, mechanoradicals, cryptoelectrons, and transfer of material. We have noticed that the extent of contact electrification of solids in water is influenced by surface free energies, mobile ions, surface roughness, duration of contact, sliding speeds, and relative humidity. Herein, we present results of our experimental investigation of contact electrification at the following interfaces: (i) PTFE-aluminum in air and (ii) polypropylene-water interfaces. To identify the underlying mechanism, we started with various hypotheses and exploited a variety of experimental techniques to falsify most of them until we got an answer; our techniques included high-voltage power supply (0-10,000 V), Faraday cages, Kelvin probe force microscopy, electrodeposition, X-ray photoelectron spectroscopy, energy-dispersive spectroscopy, optical microscopy, a contact angle cell, and high-speed imaging. We concluded that contact electrification at the PTFE-aluminum interface was driven by electrons transferred from aluminum to PTFE. In contrast, contact electrification at the polypropylene-water interface was driven by the specific adsorption of OH- ions onto polypropylene. These insights should be helpful in designing applications of polymers where electrical charging could have influence, or applications that could be based on electrical charging at such interfaces, such as triboelectric generator.

The master’s thesis deals with the topic new isolation lines of 110 kV. The aim is to propose new insulator hangers. The first, theoretical part focuses on the development of insulators, cutting and possibilities of application. They are the different materials that are used for the production of insulators HV, advantages and disadvantages long rod and cap and pin insulators. There are also described insulator hangers. The theoretical work is to describe thefittings for overhead transmission lines, which are, used to construct a insulator hanger. The last part of the theoretical work is intended distribution towers for overhead lines HV. The practical part deals with the design of new insulator suspensions for specific lines of 110 kV. The results are drawings newly designed hangers and a list of materials (fittings) for individual towers and the total amount of material. The practical part is calculating the differences in the conductor sag using old and new insulators hangers.

The study of topological superconductivity has been at the forefront of condensed matter physics for the past few years. Topological superconductors are predicted to have odd parity pairing and host so called Majorana fermions, which are not only of fundamental importance, but also proposed to be building blocks for fault-tolerant quantum computing. In this dissertation, we use point contact spectroscopy to study the pairing symmetry of candidate topological superconducting materials. We study proximity induced superconductivity in the topological insulator Bi2Se3 by a superconducting niobium tip, and propose a model to explain its features in point contact spectra. We further study the nature of the superconductivity in highly doped superconducting topological insulators, including CuxBi2Se3 and Sn1-xInxTe, using both a normal metal gold tip and a superconducting niobium tip. For CuxBi2Se3, we observe a robust zero-bias conductance peak (ZBCP) in the differential conductance spectra with the gold point contact, while with the niobium point contact we find the height of the peak exhibiting unusual non-monotonic temperature dependence. We argue that both observations cannot be explained by Andreev reflection within the standard Blonder-Tinkham-Klapwijk (BTK) model, but signify unconventional superconductivity in the material. For Sn1-xInxTe samples, we observe ZBCP in the differential conductance spectra with the gold point contact, while with the niobium point contact, the temperature dependence of ZBCP is monotonic as expected from conventional theory, leaving the nature of the superconductivity of Sn1-xInxTe still an open question.

The ruthenates are perhaps one of the most diverse group of materials known up to date. These compounds exhibit a wide array of behaviors ranging from the exotic pwave superconductivity in Sr2RuO4, to the itinerant ferromagnetism in SrRuO3, and the Mott-insulating behavior in Ca2RuO4. One of the most intriguing compounds belonging to this group is Ca3Ru2O7 which is known to undergo an antiferromagnetic ordering at 56K and an insulating transition at 48K. Most intriguing, however, is the behavior displayed by this compound in the presence of an external magnetic field. For fields parallel to the a-axis, the compound undergoes a metamagnetic transition into the ferromagnetic region at 6 T. If the external field direction is changed to the b-axis then the result will be different. colossal magnetoresistance occurs and a fall in reistivity of up to three orders of magnitude is recorded at fields of 15T. Most interesting, however, is the energy gap observed for this material. A number of groups have measured such gap with different methods and found conflicting results. For this reason it was of vital importance to perform measurements on this compound and try to resolve this issue. Tunneling spectroscopy is one of the most powerful techniques which can be used to probe the electronic properties of a material. The method is best suited to measure the density of states of a material and hence the nature of the strong correlations which dictate the properties of the compound. We performed a series of tunneling spectroscopy measurements by means of planar tunnel junctions. These types of junctions were chosen because of their stability over a large temperature range and their stability in the presence of an external field. The anisotropies which showed up in the resistivity and magnetization measurements manifested also in our data. For tunneling parallel to the a-axis, we observed a gap opening at 48K with a width a peak to peak width of 2Δa ~258±15meV. As the temperature was lowered, the gap size increased reaching a maximum width of 2Δa ~ 845±38meVat 4.2K. Tunneling parallel to the b-axis, the gap has a much smaller size than the a-axis gap. At 48K the gap width is about 2Δb ~ 201±13 meV and reaches a maximum width of 2Δb ~ 366±33 meV at 4.2K. For the c-axis, the situation is different since the gap opens at 56K instead of 48K. The gap width at 56K is about 2Δc ~ 102±6meV and reaches a maximum width of 2Δc ~ 179±14 meV at 4.2K. In the presence of an external field, we noticed that the overall behavior was always the same in the ab-plane but differed in c-axis direction. In our experiment, an external field was applied along the a-axis and measurements were made at 4.2K. For aaxis tunneling, the gap width decreased to a value of 2Δa ~ 587±27 meV at 4.2 K at 7T. On the other hand, the gap width in the b-axis direction decreased to a value of 2Δb ~ 308±25 meV for the same field. For the c-axis direction, the gap decreased to a value of 2Δc ~ 112±8 meV at 7T. The DOS of the c-axis differs for fields of 6T and above. A third peak emerges inside the gap on the valence side of the DOS. This third peak seems to be a direct consequence of the metamagnetic transition at 6T observed by other groups and may be attributable to a spin-filtering effect.

Master of Science / Department of Electrical and Computer Engineering / William Kuhn / Studies of Silicon-on-Sapphire (SOS) CMOS device operation in cryogenic environments are presented. The main focus was to observe the characteristic changes in high, medium and low threshold SOS NFETs as well as SOS silicide blocked (SN) resistors when the operational temperature is in the devices’ freeze-out range below 77 Kelvin. The measurements taken will be useful to any integrated circuit (IC) designer creating devices based on an SOS process intended to operate in cryogenic environments such as superconducting electronics and planetary probes. First, a 1N4001 rectifier and a 2N7000 NFET were tested to see how freeze-out effects standard diode and MOS devices. These devices were tested to see if the measurement setup could induce carrier freeze-out. Next, SOS devices were studied. Data was collected at room temperature and as low as 5 Kelvin to observe resistance changes in an SN resistor and kink effect, threshold voltage shifts and current level changes in transistors. A 2μm high threshold NFET was tested at room temperature, 50 Kelvin, 30 Kelvin and 5 Kelvin to observe effects on I-V curves at different temperatures with-in the freeze-out range. A 2μm medium threshold NFET was tested down to 56 Kelvin to see if the behavior is similar to the high threshold FET. A 2μm intrinsic, or low threshold, NFET was also tested with the assumption it would be the most susceptible to carrier freeze-out. All of the devices were found to behave well with only mild effects noted.

No presente trabalho foi desenvolvida uma teoria de característica elétrica da estrutura metal-isolante-metal considerando uma camada fina de óxido entre o metal e o isolante, sendo o óxido um outro isolante de banda de energia proibida mais larga. Foi considerada uma distribuição energética uniforme de estados de impurezas à interface óxido-isolante. Estudamos a distribuição real do potencial na região de carga espacial usando a equação de Poisson. Através desta distribuição obtemos a relação entre o potencial de contato e a carga positiva na região de depleção e assim a característica capacitância-voltagem da estrutura. Este tipo de característica é útil para se calcular as características corrente em função do potencial e corrente em função do tempo para um dado potencial e deste modo é importante para o entendimento das estruturas MIM e MOIM. / In this work we have developed a theory of electric characteristic of the metal-oxide-insulator-metal structure, considering a thin film of oxide between metal and insulator; the oxide is another insulator of wider forbidden energy gap. A uniform energy distribution of impurity states at the oxide-insulator interface was considered. W e have studied the actual distribution of potential in the region of spatial charge using the Poisson equation. With this distribution we obtain the relation between the contact potential and the charge in the depletion region and then the characteristic potential - capacitance of t his structure. This type of characteristic is useful to calculate the characteristic current - potential, and current-time at a given potential . In this manner it is important to the understanding of MIM and MOIM structures.

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