Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Download Anomolous Transport Properties In Highly Epitaxial Complex Oxide Thin Film full books in PDF, epub, and Kindle. Read online Anomolous Transport Properties In Highly Epitaxial Complex Oxide Thin Film ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Author : Chunrui Ma
Publisher :
ISBN 13 :
Total Pages : 210 pages
Book Rating : 4.:/5 (841 download)
Download or read book Anomolous Transport Properties in Highly Epitaxial Complex Oxide Thin Film written by Chunrui Ma and published by . This book was released on 2012 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Junsoo Shin
Publisher :
ISBN 13 :
Total Pages : 207 pages
Book Rating : 4.:/5 (179 download)
Download or read book Structure and Transport Properties of Epitaxial Oxide Thin Films written by Junsoo Shin and published by . This book was released on 2007 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: Epitaxial thin films and heterostructures based on perovskite oxides have attracted significant attention in physics since perovskites exhibit an enormous range of electrical, magnetic, and optical properties, making them exciting systems for studies of the fundamental physical mechanisms of interactions between electron, lattice, and spin degrees of freedom. This dissertation has been focused on ferroelectricity in low-dimensional ferroelectric materials using ultra-thin ferroelectric epitaxial films (BaTiO3) with a metallic electrode (SrRuO3) by studying polarized ordering of the crystal structure and electronic transport through the films. High quality and highly oxidized epitaxial films are a prerequisite for the clear observation of physical properties such as ferroelectricity which depends on a sensitive balance of lattice structure, dynamics, and charge distribution. Measurements in low dimensional, ultra-thin films require a controlled surface status through in-situ characterization. As is demonstrated here, fundamental physical phenomena on surfaces and in ultra-thin films are easily modified due to reactivity in ambient air, even for oxide materials generally considered inert. This study is centered on in-situ low energy electron diffraction and scanning tunneling spectroscopy of BaTiO3 films grown on SrRuO3 electrodes on a SrTiO3 substrate. Results show out-of-plane polarized structure and polarization switching, which provide evidence of ferroelectricity in films down to 4 ML. Surface reconstruction in 1-2 ML thick BaTiO3 films is seriously affected by the interface between BaTiO3 films and SrRuO3 bottom electrode. Our observation in epitaxial BaTiO3 films indicates the existence of ferroelectricity with a lower limit (4 ML) for the minimum thickness than theoretical expectation (6 ML), which results from the difference of film stress, termination on films, and depolarizing screening.
Author : Yuan Lin
Publisher : John Wiley & Sons
ISBN 13 : 3527696458
Total Pages : 328 pages
Book Rating : 4.5/5 (276 download)
Download or read book Advanced Nano Deposition Methods written by Yuan Lin and published by John Wiley & Sons. This book was released on 2016-08-29 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: This concise reference summarizes the latest results in nano-structured thin films, the first to discuss both deposition methods and electronic applications in detail. Following an introduction to this rapidly developing field, the authors present a variety of organic and inorganic materials along with new deposition techniques, and conclude with an overview of applications and considerations for their technology deployment.
Author : Binod Paudel
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.4/5 (64 download)
Download or read book Epitaxial Strain, Electric Field, and Domains Controlled Functionality Modulations in Complex Oxide Heterostructures written by Binod Paudel and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The perovskite 3d- transitional metal complex oxides offer opportunities to construct artificial heterostructures and chemical doping of atoms with different atomic radii resulting in similar crystal structures but diverse functionalities. The discovery of such functionalities has been possible because of the advances in synthesis, which enables fabrication of oxide heterostructures in the form of thin films, thus providing a rich ground to study their functional response with external stimuli, such as strain, electric field, and chemical pressure. In this dissertation, I investigate how such parameters can modulate different functionalities magnetic (interfacial and bulk), transport, and optical, in the three-class of heterostructures, namely: lightly doped manganite, multiferroic heterostructures, and rare-earth chromites.In the first work, I study the magneto-electric coupling at the heterostructure interface of a ferroelectric PbZr0.2Ti0.8O3 (PZT) and ferromagnetic La0.67Sr0.33MnO3 (LSMO) layers grown on an Nb-doped SrTiO3 (001) substrate utilizing polarized neutron reflectometry (PNR) in consort with ab initio-based density functional theory (DFT) calculations. The working conditions of the functional device are mimicked by gating the heterostructure with a Pt top electrode to apply an external electric field, which alters the magnitude and switches the direction of the ferroelectric (FE) polarization, across the PZT layer. PNR results show that the gated PZT/LSMO exhibits interfacial magnetic phase modulation attributed to ferromagnetic (FM) to A-antiferromagnetic (A-AF) phase transitions resulting from the accumulation of holes. When the net FE polarization points towards the interface (positive), the interface does not undergo a magnetic phase transition and retains its global FM-ordered state. In addition to changes in the interfacial magnetic ordering, the global magnetization of LSMO increases. while switching the polarization from positive to negative and it decreases vice versa. DFT calculations indicate that this enhanced magnetization also correlates with an out-of-plane tensile strain, whereas the suppressed magnetization for positive polarization is attributed to out-of-plane compressive strain. These calculations also show the coexistence of FM and A-AF -phases at zero out of plane strain. Charge modulations throughout the LSMO layer appear to be unaffected by strain, suggesting that these charge-mediated effects do not significantly change the global magnetization. Such results verify that the interfacial magnetic modulations are due to co-action of strain- and charge-mediated effects, which dominate at different length scales. In the second work, I study the microstructural evolution induced magnetism and transport properties of ferroelastic La0.9Sr0.1MnO3 (LSMO) epitaxial thin films grown on SrTiO3 (001) substrates with different miscut angles. The substrate miscut angle plays a critical role in controlling the in-plane magnetic anisotropy. The microscopic origin of such magnetic anisotropy is attributed to the formation of anisotropic stripe domains along the step terraces at the surface. The Curie temperature is found to be decreased and magnetoresistance gradually increases with the increase in miscut angles. The magnetization in the LSMO films was found to be selectively modulated by the antiferrodistortive phase transition of the SrTiO3 substrate. This phenomenon has been qualitatively explained by a strain-modified Stoner–Wohlfarth model. We conclude that the magnetization modulation by the SrTiO3 phase transition depends on h, the ratio of the applied magnetic field to the saturation field. Such modulation is only visible with h
Author :
Publisher : Elsevier
ISBN 13 : 0080532675
Total Pages : 673 pages
Book Rating : 4.0/5 (85 download)
Download or read book Growth and Properties of Ultrathin Epitaxial Layers written by and published by Elsevier. This book was released on 1997-06-18 with total page 673 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although there has been steady progress in understanding aspects of epitaxial growth throughout the last 30 years of modern surface science, work in this area has intensified greatly in the last 5 years. A number of factors have contributed to this expansion. One has been the general trend in surface science to tackle problems of increasing complexity as confidence is gained in the methodology, so for example, the role of oxide/metal interfaces in determining the properties of many practical supported catalysts is now being explored in greater detail. A second factor is the recognition of the potential importance of artificial multilayer materials not only in semiconductor devices but also in metal/metal systems because of their novel magnetic properties. Perhaps even more important than either of these application areas, however, is the newly-discovered power of scanning probe microscopies, and most notably scanning tunneling microscopy (STM), to provide the means to study epitaxial growth phenomena on an atomic scale under a wide range of conditions. These techniques have also contributed to revitalised interest in methods of fabricating and exploiting artificial structures (lateral as well as in layers) on a nanometre scale. This volume, on Growth and Properties of Ultrathin Epitaxial Layers, includes a collection of articles which reflects the present state of activity in this field. The emphasis is on metals and oxides rather than semiconductors.
Author : Ryan Haislmaier
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (971 download)
Download or read book Strain-induced Phenomenon in Complex Oxide Thin Films written by Ryan Haislmaier and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Complex oxide materials wield an immense spectrum of functional properties such as ferroelectricity, ferromagnetism, magnetoelectricity, optoelectricity, optomechanical, magnetoresistance, superconductivity, etc. The rich coupling between charge, spin, strain, and orbital degrees of freedom makes this material class extremely desirable and relevant for next generation electronic devices and technologies which are trending towards nanoscale dimensions. Development of complex oxide thin film materials is essential for realizing their integration into nanoscale electronic devices, where theoretically predicted multifunctional capabilities of oxides could add tremendous value. Employing thin film growth strategies such as epitaxial strain and heterostructure interface engineering can greatly enhance and even unlock novel material properties in complex oxides, which will be the main focus of this work. However, physically incorporating oxide materials into devices remains a challenge. While advancements in molecular beam epitaxy (MBE) of thin film oxide materials has led to the ability to grow oxide materials with atomic layer precision, there are still major limitations such as controlling stoichiometric compositions during growth as well as creating abrupt interfaces in multi-component layered oxide structures. The work done in this thesis addresses ways to overcome these limitations in order to harness intrinsic material phenomena.The development of adsorption-controlled stoichiometric growth windows of CaTiO3 and SrTiO3 thin film materials grown by hybrid MBE where Ti is supplied using metal-organic titatnium tetraisopropoxide material is thoroughly outlined. These growth windows enable superior epitaxial strain-induced ferroelectric and dielectric properties to be accessed as demonstrated by chemical, structural, electrical, and optical characterization techniques. For tensile strained CaTiO3 and compressive strained SrTiO3 films, the critical effects of nonstoichiometry on ferroelectric properties are investigated, where enhanced ferroelectric responses are only found for stoichiometric films grown inside of the growth windows, whereas outside of the optimal growth window conditions, ferroelectric properties are greatly deteriorated and eventually disappear for highly nonstoichiometric film compositions. Utilizing these stoichiometric growth windows, high temperature polar phase transitions are discovered for compressively strained CaTiO3 films with transition temperatures in excess of 700 K, rendering this material as a strong candidate for high temperature electronic applications. Beyond the synthesis of single phase materials using hybrid MBE, a methodology is presented for constructing layered (SrTiO3)n/(CaTiO3)n superlattice structures, where precise control over the unit cell layering thickness (n) is demonstrated using in-situ reflection high energy electron diffraction. The effects of interface roughness and layering periodicity (n) on the strain-induced ferroelectric properties for a series of n=1-10 (SrTiO3)n/(CaTiO3)n superlattice films are investigated. It is found that the stabilization of a ferroelectric phase is independent of n, but is however strongly dominated by the degree of interface roughness which is quantified by measuring the highest nth order X-ray diffraction peak splitting of each superlattice film. A counter-intuitive realization is made whereby a critical amount of interface roughness is required in order to enable the formation of the predicted strain-stabilized ferroelectric phase, whereas sharp interfaces actually suppress this ferroelectric phase from manifesting. It is shown how high-quality complex oxide superlattices can be constructed using hybrid MBE technique, allowing the ability to control layered materials at the atomic scale. Furthermore, a detailed growth methodology is provided for constructing a layered n=4 SrO(SrTiO3)n Ruddlesden-Popper (RP) phase by hybrid MBE, where the ability to deposit single monolayers of SrO and TiO2 is utilized to build the RP film structure over a time period of 5 hours. This is the first time that a thin film RP phase has been grown using hybrid MBE, where an a stable control over the fluxes is demonstrated during relatively long time periods of growth, which advantageously facilitates the synthesis of high-quality RP materials with excellent structural and chemical homogeneity.Additionally, this work demonstrates some major advancements in optical second harmonic generation (SHG) characterization techniques of ferroelectric thin film materials. The SHG characterization techniques developed here proved to be the bread-and-butter for most of the work performed in this thesis, providing a powerful tool for identifying the existence of strain-induced ferroelectric phases, including their temperature dependence and polar symmetry. The work presented in this dissertation will hopefully provide a preliminary road map for future hybrid MBE growers, scientists and researchers, to develop and investigate epitaxial strain and heterostructure layering induced phenomena in other complex oxide systems.
Author : Lisa Margaret Berndt Alldredge
Publisher :
ISBN 13 :
Total Pages : 232 pages
Book Rating : 4.:/5 (123 download)
Download or read book Studies of Epitaxial Complex-oxide Thin Films and Magnetic Tunnel Junctions written by Lisa Margaret Berndt Alldredge and published by . This book was released on 2006 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Meng Gu
Publisher :
ISBN 13 : 9781267240491
Total Pages : pages
Book Rating : 4.2/5 (44 download)
Download or read book Atomic Scale Characterization of Complex Oxide Thin Films written by Meng Gu and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Materials with the ABO3 perovskite structure possess a wide variety of properties including superconductivity, ferroelectric, and magnetic properties. These properties are highly tunable due to the fact that the B site cation can assume multiple valence states and its high structural stability allows for large scale doping and strain. Due to a reduced dimensionality, two dimensional thin films and superlattices grown using techniques such as pulsed laser deposition (PLD) often possess novel properties which differ from the bulk perovskite materials. The origins of these novel properties can be traced to interfacial chemical intermixing, electronic reconstruction, strain as well as defect formation, which cause significant changes in the electronic structures. Therefore, it is crucially important to investigate the atomic and electronic structures of the functional materials in order to understand the correlation between microstructures and physical properties. Chemically-sensitive Z-contrast imaging and bonding-sensitive electron energy loss spectroscopy (EELS) in aberration corrected scanning transmission electron microscopes (STEM) can directly characterize the local structure, strain, composition and bonding on the atomic scale. Determination of the atomic and electronic structures of the interfaces and defects in the thin films can then be correlated with the magnetic and transport properties. Therefore, the understanding of the structure-property relationship for several different systems of perovskite oxide thin films and superlattices were developed on the atomic scale. Multifunctional superlattices composed of ferromagnetic (FM) La(0.7)Sr(0.3)MnO3 (LSMO) and antiferromagnetic (AFM) La(0.7)Sr(0.3)FeO3 (LSFO) have potential applications for next generation data storage and logic devices. Defect formation, driven by strain relaxation in the LSMO/LSFO superlattices can modify not only the structure and surface sharpness, but also the functional properties of the superlattice. Stacking faults were found as one efficient way of strain relaxation while maintaining robust antiferromagnetic properties for a thin [3LSMO][6LSFO] superlattice (repeating motif composed of 3 unit-cell LSMO sublayer and 6 unit-cell LSFO sublayer). On the other hand, for a fully strained [3LSMO][6LSFO], large inter-diffusion across the interface between the LSMO and LSFO layers was detected in EELS line scans, resulting in deteriorated AFM properties. When a [6LSMO][6LSFO] superlattice with one micron thickness, a high density of nanoflowers and cracks/pinholes were observed to result from strain relaxation. The formation of these nanoflowers and cracks/pinholes was suppressed by increasing the growth rate and thereby reducing the growth time and overall thermal treatment of the sample. Strain relaxation was shown to be directly related to the growth conditions and have a large effect on both the structure and functional properties of the superlattices. A series of superlattices composed of non-magnetic La(0.5)Sr(0.5)TiO3 (LSTO) and ferromagnetic LSMO were grown on single crystal oxide substrates with different amounts of misfit strain. No significant electronic structure changes along the interfaces was observed in this series of superlattices as revealed by atomic resolution EELS. In comparison, charge transfer effect was reported for the LSMO/STO superlattices and was shown to cause an ultrathin magnetic dead layer along the interfaces. Thus, compared with the LSMO/STO superlattice, composition tuning of the sublayers was proven to be efficient in controlling the interfacial charge transfer effects in a superlattice. In addition, tetragonal distortion was found to reduce the ferromagnetic ordering, decrease the Tc, increase the resistivity, and even lead to metal-insulator transitions of the superlattices. The strain relaxation defects such as dislocations and low angle grain boundaries serve as important pinning sites for magnetic domains, leading to enhanced coercive field strength. In order to determine the properties of an intermixed interface layer, we have performed a detailed study of the solid solution between LSMO and LSFO, i.e. La(0.7)Sr(0.3)Mn(0.5)Fe(0.5)O3 (LSMFO). A large target-substrate distance during the PLD growth led to cation segregation in the LSMFO film. Cation segregation could cause the formation of diverse local magnetic ordering and B site valence states due to the different local stoichiometry and coordination environment. For the cation segregated LSFMO films, robust ferromagnetic and antiferromagnetic coupling was observed at 150K and room temperature. Decreasing the target-substrate distance resulted to a homogeneous cation distribution in the film, without any ferromagnetic ordering as expected. This result suggests the important role of target-substrate distance and the kinetic energy of the plume species on the crystalline quality and functional properties of perovskite oxide thin films. La(x)Sr(1-x)TiO3 possesses a wide range of functional properties which make it an attractive candidate material for applications such as the conductive buffer for high temperature superconductor growth, transparent conductors, and anodes in solid oxide fuel cells. La(0.5)Sr(0.5)TiO3 thin films were grown using PLD and the resistivity was found to be highly dependent on the O2 background pressure used in the deposition. However, a thin film which was deposited as a single phase film was transformed into a semi-ordered superlattice with TiO2 rich stacking faults and distorted lattices upon exposure to high oxygen pressure (~200torr) during the cooling procedure after deposition. This phase change stabilized Ti4+ ions and dramatically increased the resistivity of the film. In addition, a two dimensional free electron gas could be constructed by confining a few unit cells of La doped STO with STO spacer layers. Our study showed that charge transfer over a distance of ~2 u.c. was present in Sr(0.75)La(0.25)TiO3/STO superlattices. This thickness defined the lower limit for the thickness of the STO spacers in order to confine the charge carriers into two dimensions; secondly, the La dopants were shown to be less localized in thicker superlattice (~100nm) due to interdiffusion upon extended thermal exposure. This information provided important feedback on the fabrication and utilization of this material.In conclusion, several perovskite thin film systems with fascinating properties have been explored in this thesis. Strain states and strain relaxations, defect formation, interfacial atomic mixing, charge transfer, and cation segregation were shown to have profound effect on the functional properties of complex oxide thin film systems. Atomic resolution Z-contrast imaging and EELS provide extremely useful information on the structural and electronic structure variations, which enable us to see the whole picture of growth, structure and properties' interactions.
Author : Ngai-Shek Soong
Publisher : Open Dissertation Press
ISBN 13 : 9781361192412
Total Pages : pages
Book Rating : 4.1/5 (924 download)
Download or read book Preparation and Properties of Epitaxial Thin Films of La1-Xbaxmn03 on Various Substrated written by Ngai-Shek Soong and published by Open Dissertation Press. This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Preparation and Properties of Epitaxial Thin Films of La1-xBaxMn03 on Various Substrated" by Ngai-shek, Soong, 宋毅碩, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled PREPARATION AND PROPERTIES OF EPITAXIAL THIN FILMS OF La Ba MnO ON VARIOUS SUBSTRATES 1-x x 3 submitted by Ngai-Shek SOONG for the degree of Master of Philosophy at The University of Hong Kong in December 2002 Epitaxial thin films of La Ba MnO (LBMO) were on deposited SrTiO 0.8 0.2 3 3 (100) (STO), LaAlO (100) (LAO), MgO (100) and Y O - ZrO (100) (YSZ) 3 2 3 2 substrates by using an off-axis magnetron sputtering. The properties of fabricated LBMO thin films were studied by using X-ray diffraction, dc four-probe measurements, surface profiler and atomic force microscopy. For LBMO thin films grown on STO, X-ray diffraction patterns showed that the films were highly c-axis oriented and fully epitaxial. The obtained values of full width at half maximum (FWHM) of the (002) rocking curves were small, indicating good crystallinity of the films. The temperature of insulator-metal transition, T, decreased as the thickness of the thin film increased. This was different from other systems with similar perovskite structure such as La Ca MnO and La Sr MnO . The electrical 1-x x 3 1-x x 3 resistivity of LBMO/STO thin film for temperature T2 4.5 expression of ρ(T) =ρ +ρ T +ρ T (Eq.1). The values of ρ ρ ρ all increased 0 2 4.5 0, 2, 4.5 with increasing thickness d, except d=350A, implying a phase transition may have occured. The anomalous electrical behavior of LBMO/STO system could not be explained by considering only the decreasing of transfer integral on in-plane e electrons. The orbital degree of freedom played a crucial role in determining the electrical properties of tensile-stressed LBMO thin films due to the relatively large ratio of c/a. For LBMO/LAO thin films, X-ray diffraction patterns and small FWHM values implied good crystallinity of the thin films. The decreasing value of out-of- plane lattice parameters with increasing thickness suggested the existence of compressive strain within the LBMO/LAO system. The temperature dependence of resistivity measurement showed that T decreases as the thickness of thin film increased. This is consistent with the double-exchange theory, which states that compressive strain enhances T . The temperature dependence of resistivity of LBMO/LAO thin films were also fitted well to expression (Eq.1), The values of ρ 0, ρ ρ all increased with increased thickness. 2, 4.5 La Ba MnO was also deposited on YSZ or MgO substrates respectively, 0.8 0.2 3 which having larger lattice mismatch. Peaks other than (00l) orientation were observed in X-ray measurements indicating the thin films were c-axis oriented but not highly epitaxial. A fairly large value of the FWHM of the (002) diffraction peak suggested that the films were highly crystalline. Insulator-metal (I-M) transition were not observed in LBMO/MgO films and only appear in LBMO/YSZ films with d>1200A. These were mainly due to that large lattice mismatches between LBMO and YSZ or MgO substrates which generate a large number of grains and grain boundaries in the thin films, which in turn decrease the electron transfer integral. DOI: 10.5353/th_b2663683 Subjects: Thin films Epitaxy
Author : Ashish Garg
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (16 download)
Download or read book Growth and Characterization of Epitaxial Oxide Thin Films written by Ashish Garg and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Epitaxial oxide thin films are used in many technologically important device applications. This work deals with the deposition and characterization of epitaxial WO3 and SrBi2Ta2O9 (SBT) thin films on single crystal oxide substrates. WO3 thin films were chosen as a subject of study because of recent findings of superconductivity at surfaces and twin boundaries in the bulk form of this oxide. Highly epitaxial thin films would be desirable in order to be able to create a device within a film without patterning it, by locally creating superconducting regions (e.g. twins) within an otherwise defect free film by reducing or doping the film with Na. Films were deposited by reactive magnetron sputtering at various temperatures on single crystal SrTiO3 (100) and R-sapphire substrates. X-ray diffraction studies showed that the optimised films were highly (001) oriented, quality of epitaxy improving with decreasing deposition temperature. AFM studies revealed columnar growth of these films. Films were heat treated with Na vapour in order to reduce or dope them with Na. Low temperature measurements of the reduced films did not show existence of any superconductivity. SBT is a ferroelectric oxide and its thin films are attractive candidates for non-volatile ferroelectric random access memory (FRAM) applications. High structural anisotropy leads to a high degree of anisotropy in its ferroelectric properties which makes it essential to study epitaxial SBT films of different orientations. In this study, SBT films of different orientations were deposited on different single crystal substrates by pulsed laser ablation. Highly epitaxial c-axis oriented and smooth SBT films were deposited on SrTiO3 (100) substrates. AFM studies revealed the growth of these films by 3-D Stranski-Krastanov mode. However, these films did not exhibit any ferroelectric activity. Highly epitaxial (116)-oriented films were deposited on SrTiO3 (110) substrates. These films were also very smooth with root mean square (RMS) roughness of 15-20 Å. Films deposited on TiO2 (110) were partially a-/b-axis oriented and showed the formation of c-axis oriented SBT and many impurities. Completely a-/b-axis oriented SBT films were deposited on LaSrAlO4 (110) substrates. Films deposited at non-optimal growth temperatures showed the formation of many impurities. Attempts were also made towards depositing Sr2RuO4 films on LaSrAlO4 (110) substrates, which can act as a bottom electrode for ferroelectric SBT films.
Author : Joseph A. Cianfrone
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (755 download)
Download or read book Functional Complex Oxide Thin Films and Related Superlattices Grown Via Pulsed Laser Deposition written by Joseph A. Cianfrone and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Oxide electronics offer a wide array of interesting properties, including ferromagnetism, ferroelectricity and superconductivity. This dissertation investigates the transport, magnetic, and structural properties of several perovskite and spinel material systems, with particular interest in their manipulation at the nanoscale through the growth of functional heterostructures. Spinel phase ZnCo2O4 is investigated as a ferromagnetic semiconductor whose carrier type changes with oxygen concentration. The perovskite system of K(Ta, Nb)O3 is investigated for its interesting properties as a solid solution which exhibits a ferroelectric transition dependent on composition. Its thin film epitaxial growth modes are investigated via reflection high energy electron diffraction, with particular attention paid to the volatile potassium ion. Superlattices of K(Ta, Nb)O3 and SrTiO3 are also investigated for the possibility of dielectric enhancement and conductive interfaces. The multiferroic properties of BaFeO3 K(Ta, Nb)O3 superlattices are investigated, with particular attention paid to the role of magnetoelectric coupling and strain as stabilizing mechanisms.
Author : James S. Speck
Publisher :
ISBN 13 :
Total Pages : 588 pages
Book Rating : 4.:/5 (318 download)
Download or read book Epitaxial Oxide Thin Films II: Volume 401 written by James S. Speck and published by . This book was released on 1996-03-29 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our understanding and control of epitaxial oxide heterostructures has progressed along multiple frontiers including magnetic, dielectric, ferroelectric, and superconducting oxide materials. This has resulted in both independent rediscovery and the successful borrowing of ideas from ceramic science, solid-state physics, and semiconductor epitaxy. A new field of materials science has emerged which aims at the use of the intrinsic properties of various oxide materials in single-crystal thin-film form. Exploiting the potential of these materials, however, will only be possible if many fundamental and engineering questions can be answered. This book represents continued progress toward fulfilling that promise. Technical information on epitaxial oxide thin films from industry, academia and government laboratories is presented. Topics include: dielectrics; ferroelectrics; optics; superconductors; magnetics; magnetoresistance.
Author : Hao Zhang
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (133 download)
Download or read book Novel Phases in Hetero-Epitaxial and Super-Oxygenated Thin Films of Complex Oxides written by Hao Zhang and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis we study structural phase transition and defect structures in complex oxide thin films induced by either heterostructuring or superoxygenation, in an effort to understand their effects on the electronic and superconducting properties. Thin films were chosen for the ability to tune the heteroepitaxial strain, as well as their large surface-to-volume ratio. We focus on two families of oxides, including the cuprate superconductors Y-Ba-Cu-O (YBCO), and the Ruddlesden-Popper iridates Sr(n+1)Ir(n)O3(n+1). We examine the effect of heteroepitaxial strain on the superconducting critical temperature (Tc) of YBa2Cu3O(7-x) (YBCO-123) thin film. Strain-induced intergrowth of CuO defect structures is seen in La(2/3)Ca(1/3)MnO3 (LCMO)/YBCO-123 bilayer films, and can account for the reduced Tc in such bilayers. Perovskite/YBCO-123/perovskite trilayers with either ferromagnetic LCMO or paramagnetic LaNiO3 (LNO) as clamping layers show similarly strong reduction of the Tc. The Tc reduction is much milder when orthorhombic PrBa2Cu3O(7-x) (PBCO) is used as clamping layers instead. These results indicate that heteroepitaxial strain, rather than long-range proximity effect, is responsible for the long length scales of Tc reduction in LCMO/YBCO-123 heterostructures. We carried out superoxygenation experiments on YBCO-123 films in order to search for novel YBCO phases. YBCO-123 films are annealed in high-pressure oxygen, in conjunction with Cu enrichment by solid-state diffusion. The annealed films show clear evidence of phase transformation to Y2Ba4Cu7O(15-x) and Y2Ba4Cu8O16, increasing with higher degree of Cu enrichment. Regions of exotic phases containing multiple CuO or Y layers are also seen in high-pressure annealed films. Our results demonstrate a novel route of synthesis towards discovering more complex YBCO phases. We also carried out superoxygenation on Sr2IrO4 (SIO) films in an attempt to metallize the iridates via hole-doping. High-pressure oxygen annealed SIO films show a progressive drop in room-temperature resistivity of up to 3 orders of magnitude, and an evolution towards metallic behavior. The post-annealed films show transformation to SrIr(1-x)O3, increasing with annealing time, pressure, and reduced film thickness. The evolution towards metallicity is attributed to phase transformation, interstitial oxygens, and Ir vacancies. The Ir vacancies in the most phase-transformed film appears to be structurally-ordered along the c-axis. Our results demonstrate a novel method for hole-doping and phase-transforming the iridates.
Author : Kyeong-Won Kim
Publisher :
ISBN 13 :
Total Pages : 121 pages
Book Rating : 4.:/5 (857 download)
Download or read book Growth and Characterizations of Complex Oxide Thin Film Heterostructures Via Pulsed Laser Deposition written by Kyeong-Won Kim and published by . This book was released on 2012 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: The superlattices showed the strain induced enhancement of magnetization and the Curie temperature of superlattices were lowered substantially with increasing strain. Phosphorus doped ZnOthin films were deposited on ZnO buffer grown under different growth conditions and the properties of thin films were examined, focusing on the role of buffer layers. Phosphorus doped ZnO thin films on buffer layer grown at low temperature were less conductive as grown state and showed a drastic change in the transport properties upon the rapid thermal annealing. This suggests that poor crystalline quality of the buffer layer grown at low temperature lead to the more incorporation of phosphorus dopants in following films. A high resolution X-ray diffraction study confirmed the poor crystalline quality of phosphorus doped thin films on low temperature deposited buffer layer by broader peaks of omega rocking curves. Also it was observed that the microstructures of the phosphorus doped ZnO thin film significantly depended on the buffer layer.
Author : Chang-Beom Eom
Publisher : Materials Research Society
ISBN 13 : 9781558993785
Total Pages : 0 pages
Book Rating : 4.9/5 (937 download)
Download or read book Epitaxial Oxide Thin Films III: Volume 474 written by Chang-Beom Eom and published by Materials Research Society. This book was released on 1997-09-10 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As a result of the progress towards, and potential realized in electronic and optical device applications, the interest in epitaxial oxide thin films continue to flourish. The understanding of epitaxial oxide heterostructures has progressed, including magnetic, magnetoresistive, dielectric, ferroelectric and superconducting oxide materials. This book focuses on the fundamental issues of oxide epitaxy, microstructural evolution in epitaxy, and physical properties of epitaxial oxide thin films and how these issues relate to device applications. The book provides a vehicle through which groups of scientists working on a set of diverse phenomena could interact and present findings on very common specific themes involving similar materials. Due to the explosive growth of work in the area of colossal magnetoresistive (CMR) materials, especially in epitaxial form, the book also offers a forum to critically examine the fundamental nature of CMR in epitaxial oxide thin films and the relationship between CMR and defect structure. Other areas of emphasis include: ferroelectric memories, nonlinear optical waveguides, microwave electronics and magnetic oxide thin films.
![Download Electrical Transport Properties of Epitaxial and Granular Oriented YBa2Cu3O--[̲delta] Thin Films PDF Online Free](https://books.google.com/books/content/images/frontcover/vcpjNwAACAAJ?fife=w200-h370)
Author : Edwin C. Jones
Publisher :
ISBN 13 :
Total Pages : 394 pages
Book Rating : 4.:/5 (293 download)
Download or read book Electrical Transport Properties of Epitaxial and Granular Oriented YBa2Cu3O--[̲delta] Thin Films written by Edwin C. Jones and published by . This book was released on 1992 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Jonathon Lee Schad
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (139 download)
Download or read book Development of Synthesis Routes for Epitaxial Oxide Thin Films written by Jonathon Lee Schad and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using the deposition method best suited for depositing an oxide thin film can be the difference between measuring the intrinsic properties of the thin film and measuring extrinsic properties arising from defects, impurity phases, and contamination. In this work, unique synthesis routes for the deposition of three epitaxial oxide thin films is presented. Applying these new routes, new material properties were able to be discerned that had been concealed in thin films deposited utilizing conventional methods. Dual off-axis RF sputtering of Bi-rich BiFeO3̳ targets was employed to deposit a 1 [mu]m-thick multiferroic BiFeO3̳ film on various (111)p̳c̳-orientated substrates with cubic and orthorhombic symmetries. Using non-resonant x-ray magnetic scattering (NXMS) and neutron diffraction, the magnetic domain populations in the BiFeO3̳ were measured. We found that growing on reduced-symmetry substrate NdGaO3̳ (011)o̳, yields a BiFeO3̳ film with a single ferroelectric, structural, and magnetic domain consistent across the whole sample. The single domain remains stable even after switching a region of the sample ferroelectrically up to 10,000 times. Using NXMS polarimetry we confirm that there is a change in the magnetic polarity of the BiFeO3̳ domain after ferroelectric switching, demonstrating the coupling of the magnetic and ferroelectric orders in monodomain (111)p̳c̳-orientated BiFeO3 ̳ thin films. Using reactive RF sputtering of a pure Fe target, phase pure deposition of antiferromagnetic insulator [alpha]-Fe2O3̳ was achieved. SQUID magnetometry confirms the absence of any ferromagnetic minority domains in the film. We showed that the Morin transition temperature, above which [alpha]-Fe2̳O3̳ has a weak canted moment, decreases when reducing the thickness of the film. For films 10 nm and thinner, the Morin transition was suppressed completely. Using the XMLD contrast of the 10 nm-thick [alpha]-Fe2̳O3̳ film, X-ray Photoemission Electron Microscopy (PEEM) measurements uncovered a complex mosaic of sub-micron size antiferromagnetic domains connected by a network of antiferromagnetic spin vortices. The vortices were mostly found in vortex/antivortex pairs which could be annihilated through the application of an external magnetic field. When a 1 nm-thick Co layer was overlayed, the mosaic of domains present in the [alpha]-Fe2̳O3̳ was coupled to the Co which takes on the same mosaic pattern. Pulsed laser deposition of SrO and chemical vapor deposition of a TiO2̳ precursor gas were used simultaneously to deposit high quality SrTiO3 thin films in a hybrid deposition technique we called metal-organic pulsed laser deposition (MOPLD). We demonstrated a conductive 2-dimensional electron gas (2DEG) at the interface between MOPLD-grown SrTiO3 and PLD-grown LaAlO3̳, indicative that the SrTiO3̳ thin film is highly stoichiometric. The increased stoichiometry control afforded by MOPLD also grants the ability to control the point defects in the system. By decreasing the abundance of point defects, quantum properties of SrTiO3̳ become accessible.
