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Book Growth and Characterization of Magnetic and Superconducting Thin Films Based on Polifunctional Perovskite Oxides Heterostructures

Download or read book Growth and Characterization of Magnetic and Superconducting Thin Films Based on Polifunctional Perovskite Oxides Heterostructures written by Norberto Gabriel Boggio and published by . This book was released on 2006 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Perovskite Oxide Thin Film Growth  Characterization  and Stability

Download or read book Perovskite Oxide Thin Film Growth Characterization and Stability written by Andrew Izumi and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies into a class of materials known as complex oxides have evoked a great deal of interest due to their unique magnetic, ferroelectric, and superconducting properties. In particular, materials with the ABO3 perovskite structure have highly tunable properties because of the high stability of the structure, which allows for large scale doping and strain. This also allows for a large selection of A and B cations and valences, which can further modify the material's electronic structure. Additionally, deposition of these materials as thin films and superlattices through techniques such as pulsed laser deposition (PLD) results in novel properties due to the reduced dimensionality of the material. The novel properties of perovskite oxide heterostructures can be traced to a several sources, including chemical intermixing, strain and defect formation, and electronic reconstruction. The correlations between microstructure and physical properties must be investigated by examining the physical and electronic structure of perovskites in order to understand this class of materials. Some perovskites can undergo phase changes due to temperature, electrical fields, and magnetic fields. In this work we investigated Nd0.5Sr0.5MnO3 (NSMO), which undergoes a first order magnetic and electronic transition at T=158K in bulk form. Above this temperature NSMO is a ferromagnetic metal, but transitions into an antiferromagnetic insulator as the temperature is decreased. This rapid transition has interesting potential in memory devices. However, when NSMO is deposited on (001)-oriented SrTiO3 (STO) or (001)-oriented (LaAlO3)0.3-(Sr2AlTaO6)0.7 (LSAT) substrates, this transition is lost. It has has been reported in the literature that depositing NSMO on (110)-oriented STO allows for the transition to reemerge due to the partial epitaxial growth, where the NSMO film is strained along the [001] surface axis and partially relaxed along the [11̄0] surface axis. This allows the NSMO film enough freedom of movement to undergo a shear strain along the [11̄0] axes, allowing the NSMO film to switch phases. It was found that the desired magnetic and electrical properties were closely tied to the structural properties, which were highly sensitive to the precise growth conditions. These perovskite oxides can be further geometrically constrained by patterning, resulting in additional novel magnetic and electrical properties. One such method of patterning involves implanting Ar into a film to locally destabilize the ordered perovskite structure, therefore suppress the magnetic and electrical properties. However, to fully integrate this technique into devices which require multi-planar processes, the ability for a patterned perovskite film to withstand high temperature anneals is crucial in creating more advanced structures. The stability of Ar-implanted La0.7Sr0.3MnO3 (LSMO) thin films was studied upon annealing at 400°C, 500°C, and 600°C. The LSMO retained its amorphous structure with little ferromagnetism after a 400°C anneal, but anneals at 500°C and 600°C resulted in partial recrystallization and a return of the ferromagnetic properties. This recrystallized film displayed semiconducting properties with a lower Curie temperature than the as deposited film. The deposition of an La0.7Sr0.3FeO3 (LSFO) film onto an Ar implanted LSMO film at 400°C caused the LSMO film to almost fully recrystallize, suggesting that the deposition process also recrystallizes the Ar-implanted film. In conclusion, two perovskites films were explored in this thesis. NSMO films proved to be very sensitive to growth conditions, and Ar-implanted LSMO films quickly recrystallized past 400°C or a subsequent film deposition. These studies provide useful information on the structural and electronic transformations these films go through during heat treatment and strain engineering.

Book A Study of Structure Induced Phase Phenomena in Perovskite Oxide Thin Films

Download or read book A Study of Structure Induced Phase Phenomena in Perovskite Oxide Thin Films written by Jason Lapano and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The three core tenants of materials science are theory, synthesis, and characterization. A solid theoretical framework is required for understanding of the problem at hand and using that knowledge to advance new areas of research. Synthesis of pristine materials is required to study the theory in a physical system and prevent misinterpretation of results. Complex structures and compositions are often the most interesting, and when defects and impurities are of interest, perfectly-imperfect samples are required which are often the most challenging to synthesize. Characterization of these materials is equally as important and complex, requiring careful sample preparation and experimental setups. Further, it is not always clear how to observe the property of scientific interest, and new characterization techniques must be developed. This dissertation focuses on using these three tenants to understand and advance the field of transition metal perovskite complex oxides using thin films of the incipient ferroelectrics CaTiO3 and SrTiO3 and antiferromagnetic Mott-Insulators LaVO3 and YVO3. The knowledge gained in this thesis can be applied to other complex oxide materials in better understanding magnetic and electronic transitions, high Tc superconductivity and quantum hall effect. Coupled with the relatively simple structure and ease of integration of multiple different chemical compounds into a single heterostructure leads to near numerous avenues to design functionality into materials.The first sections of this thesis begin with (1) an introduction to the basic science and past work in perovskite oxides, followed by (2) exploring the most common and promising synthesis routes, and finally (3) the various characterization methods used. The 4th chapter addresses the specific challenges of growth of ternary complex oxide thin films in an industrially profitable fashion. The three primary criterion that these deposition methods must adhere to is that they must (a) control film stoichiometry to less than 1% deviations, (b) deposit conformal coatings over standard 8 silicon wafers, (c) and exhibit deposition rates in excess of 1 m/hr. We show that these can be achieved using a hybrid molecular beam (hMBE) epitaxy approach and outline a route for commercially viable growth of complex oxides on silicon. This method is applied directly to the deposition of SrTiO3 on silicon for virtual single crystal perovskite substrates. The 5th chapter of this thesis discusses the effect of epitaxial strain, stoichiometry and interfacial coupling in heterostructures of complex oxides. In the (SrTiO3)n(CaTiO3)n series of superlattices grown by hMBE, it is found that interfacial energies play a large role in dictating the macroscopic properties, particularly ferroelectricity. In coherently strained thin films, both CaTiO3 and SrTiO3 exhibit relaxor-like ferroelectric behavior below room temperature. However, certain superlattices of these materials show nonpolar behavior when probed using second harmonic generation (SHG). High resolution scanning transmission electron microscopy (STEM) reveals that the symmetry in the superlattice is different from the individual parent compounds at the same strain state. It is found these are directly related to the high density of interfacial layers present in the films. Further, interfacial mixing of the constituent layers on certain superlattices leads to the development of a Ca1-xSrxTiO3 alloy which develops a ferroelectric moment at low temperatures, leading to spurious SHG signals. The findings of this experiment highlight the sensitivity of these complex layered structures to strain, stoichiometry, distortion coupling effects, and interfacial mixing.

Book Thin Films and Heterostructures for Oxide Electronics

Download or read book Thin Films and Heterostructures for Oxide Electronics written by Satishchandra B. Ogale and published by Springer. This book was released on 2008-11-01 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oxides form a broad subject area of research and technology development which encompasses different disciplines such as materials science, solid state chemistry, physics etc. The aim of this book is to demonstrate the interplay of these fields and to provide an introduction to the techniques and methodologies involving film growth, characterization and device processing. The literature in this field is thus fairly scattered in different research journals covering one or the other aspect of the specific activity. This situation calls for a book that will consolidate this information and thus enable a beginner as well as an expert to get an overall perspective of the field, its foundations, and its projected progress.

Book Synthesis and Characterization of Ferromagnetic antiferromagnetic Perovskite Oxide Superlattices

Download or read book Synthesis and Characterization of Ferromagnetic antiferromagnetic Perovskite Oxide Superlattices written by Yue Jia and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Perovskite oxides span a diverse range of functional properties such as ferromagnetism, superconductivity, and ferroelectricity, which makes them promising candidate materials for applications such as sensors, energy conversion and data storage devices. With recent advances in thin film deposition techniques, the precise manipulation of atomic layers on the unit cell level make it possible to synthesize epitaxial thin film heterostructures consisting of layers with different properties. The structural compatibility of perovskite oxides allows them to be epitaxially grown in complex heterostructures such as superlattices with a large density of interfaces where the interplay between spin, charge, orbital, and lattice degrees of freedom gives rise to new behaviors. The ferromagnetic (FM)/antiferromagnetic (AF) interface is particularly interesting due to exchange coupling which is not only of interest for fundamental research but also is of great significance for industrial applications[superscript 1,2]. Unlike metallic systems that have been studied for decades with wide ranges of applications in devices such as hard disk drives, thin films of complex metal oxides is a relatively new field. Perovskite oxides show much more diverse functional properties than metals and open new pathways for tailoring propertiestowards specific device applications. Epitaxial La[subscript 0.7]Sr[subscript 0.3]MnO3 (LSMO)/La[subscript 0.7]Sr[subscript 0.3]FeO3 (LSFO) superlattices serve as model systems to explore the magnetic structure and exchange coupling at perovskite oxide interfaces. Earlier work suggested that (001)-oriented LSMO/LSFO superlattices with compensated AF spins at the interface display spin-flop coupling characterized by perpendicular alignment between the AF spin axes and the FM moments at a sublayer thickness of 6 unit cells (u.c.) [superscript 3-5]. Changing the crystallographic orientation of the interface from (001) to (111) introduces changes to factors such as the charge density of each stacking layer, the magnetic structure of the AF layer at the interface, the symmetry of the lattice, and the orbital degeneracy. Therefore, different properties and exchange coupling mechanisms are expected. (111)-oriented LSMO/LSFO superlattices with sublayer thicknesses ranging from 3 to 60 u.c. were synthesized and characterized. Detailed analysis of their structural, electronic, and magnetic properties were performed using synchrotron radiation based resonant x-ray reflectivity, soft x-ray magnetic spectroscopy, and photoemission electron microscopy to explore the effect of sublayer thickness on the magnetic structure and exchange coupling at (111)-oriented perovskite oxide interfaces. Interfacial effects and ultrathin superlattice sublayers can stabilize orientations of the LSFO AF spin axis which differ from that of LSFO films and LSMO/LSFO bilayers. In the ultrathin limit (3 to 6 u.c.), it was found that the AF properties of the LSFO sublayers are preserved with an out-of-plane canting of the AF spin axis, while the FM properties of the LSMO sublayers are significantly depressed. For thicker LSFO layers (> 9 u.c.), the out-of-plane canting of the AF spin axis is only present in superlattices with thick LSMO sublayers. As a result, exchange coupling in the form of spin-flop coupling exists only in superlattices which display both robust ferromagnetism and out-of-plane canting of the AF spin axis. A portion of the AF moments can be reoriented by a moderate external magnetic field through spin-flop coupling with the FM LSMO sublayers that have low magnetocrystalline anisotropy in the (111) plane. The AF order in the spin-flop coupled superlattices was studied using angle-dependent x-ray magnetic linear dichroism. The AF order can be categorized into two types: majority of the AF moments cant out-of-the-plane of the film along the 110 or 100 directions depending on the LSFO layer thickness, while a minority portion lies within the (111) plane in different AF domains. The energy difference between domains with their spin axes along the in-plane or out-of-plane directions is small, and the magnetic order of AF thin films is far more complex than in bulk LSFO. The complex AF structure in these (111)-oriented LSMO/LSFO superlattices illustrates that complex metal oxide heterostructures can serve as fertile ground for discovery of new magnetic phases, which have potential applications in next generation information technology devices.

Book Structural Characterization of Perovskite Thin Films by X ray Reflectivity

Download or read book Structural Characterization of Perovskite Thin Films by X ray Reflectivity written by Jinyun He and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Perovskite oxides are a unique class of materials possessing a wide range of functional properties that stem from their spin, charge, lattice, and orbital degrees of freedom. The perovskite oxide exchange spring heterostructure, comprised of a hard and a soft magnetic layer, has similar properties to its metallic counterpart, but can be fine-tuned with intrinsic and extrinsic parameters such as chemical doping, lattice strain, and applied electric/magnetic fields. In this thesis, single layer La0.7Sr0.3CoO3 (LSCO) and La0.7Sr0.3MnO3 (LSMO) thin films on (LaAlO3)0.3(Sr2TaAlO6)0.7 (LSAT) substrates and bilayer LSCO/LSMO heterostructures on LSAT and NdGaO3 (NGO) substrates were grown by pulsed laser deposition. The magnetic properties of the samples were characterized by X-ray Absorption (XA) and X-ray magnetic circular dichroism (XMCD) and the structural properties were characterized by hard and soft X-ray Reflectivity (XRR). The XRR data measured at the Mn and Co L-edge energies were analyzed by fitting in the software ReMagX. Combined with the other techniques, the fitting of the XRR data was able to determine the best structural models for the samples, provide thickness and roughness values for each layer with a sub-Angstrom resolution, and aid in obtaining the optical constants of the materials. XRR was proved to be a powerful non-destructive technique in probing the structural profiles of the complex thin film heterostructures.

Book Investigating Quadruple Perovskites

Download or read book Investigating Quadruple Perovskites written by Amanda Huon and published by . This book was released on 2018 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: The miniaturization trend in conventional electronics is approaching the limits beyond which the reduction of the electronic element is becoming more and more difficult. One way to continue the current trends in computer power and data storage increase without further size reduction is to use new functionalities such as charge-ordering or multiferroic behavior in devices. Complex oxide heterostructures are a materials platform that exhibit an unmatched array of collectively ordered states, including magnetism, ferroelectricity, and charge/orbital ordering, and are being researched for potential device applications. As a member of the quadruple perovskite family, CaMn7O12 exemplifies the rich physics that complex oxides can host. Previous work shows that this material in bulk form exhibits four distinct phase transitions: a charge-ordering transition at 430 K, an orbital ordering transition at 250 K, and two magnetic transitions at 90 K (TN1) and 45 K (TN2). Additionally, the magnetic ordering at TN1 induces ferroelectricity, which is the largest magnetically induced polarization yet reported. Despite the scientific interest and the technological potential for this material, there have been no reports of CaMn7O12 films prior to this thesis work. This dissertation is focused on establishing growth conditions for CaMn7O12 quadruple perovskite thin films using molecular beam epitaxy and pulsed laser deposition methods. By synthesizing thin films using both methods, I identify the key parameters in establishing the growth conditions for phase-pure CaMn7O12 films by evaluating cation stoichiometry and structural properties. To develop insight into the role of thin film structure-property relations, I explore how the electronic and magnetic structures of thin films compare to bulk. Then I develop insight into quadruple manganites by elucidating how the electronic and magnetic properties are tuned by chemical pressure effects through A-site substitution in Ca1-xSrxMn7O12 films. I identified the changes in charge-ordering, magnetic ordering, and helical spin structure through Sr-doping up to x ~ 0.6 by transport, magnetometry, and neutron diffraction measurements. These results provide fundamental insights into quadruple perovskite film synthesis and serve as a catalyst for future studies focused on AMn7O12 thin films. The material understanding of CaMn7O12 films obtained from this dissertation offers new avenues in the search and control of new functionalities in oxide heterostructures.

Book Structure and Transport Properties of Epitaxial Oxide Thin Films

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.

Book Growth and Characterization of Sr2FeMoO6 Thin Films on Ceramic Substrates

Download or read book Growth and Characterization of Sr2FeMoO6 Thin Films on Ceramic Substrates written by Santosh Kumar Myana and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal oxide heterostructures are known to have shown a wide range of phenomenal properties such as superconductivity, colossal magnetoresistance and multiferroicity. The double perovskite Sr2FeMoO6 (SFMO) is reported to be a ferrimagnetic with high Curie temperature (410 - 450 K), which exhibits an appreciable low field magnetoresistance (LFMR) even at room temperature. Most of the thin film systems are prepared on single crystal substrates such as SrTiO3, LaAlO3, MgO and some limited compositions with few low index orientations available. Here, we used a throughput synthesis technique called Combinatorial Substrate Epitaxy , where we deposit thin films on isostructural polycrystalline substrates, using optimized deposition conditions. We investigate the deposition of SFMO thin films on three different polycrystalline substrates such as Sr2MgWO6 (SMWO), Ba2MgWO6 (BMWO) and Ca2MgWO6 (CMWO), and correlate the structural and electronic properties with the compositions, the strains and nature of defects.

Book Growth and Characterization of Superconducting Spinel Oxide LiTi2O4 Thin Films

Download or read book Growth and Characterization of Superconducting Spinel Oxide LiTi2O4 Thin Films written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Epitaxial films of LiTi2O4 on single crystalline substrates of MgAl2O4, MgO, and SrTiO3 provide model systems to systematically explore the effects of lattice strain and microstructural disorder on the superconducting state. Lattice strain that affects bandwidth gives rise to variations in the superconducting and normal state properties. Microstructural disorder, such as antiphase boundaries that give rise to Ti network disorder, reduces the critical temperature, and Ti network disorder combined with Mg interdiffusion lead to a much more dramatic effect on the superconducting state. Surface sensitive X-ray absorption spectroscopy has identified Ti to retain site symmetry and average valence of the bulk material regardless of film thickness.

Book Thin Film Growth of Cuprate and Ruthenate Perovskites and Electronic Characterization of the Electron doped Superconductor Nd  2   x  Cex  CuO  4      delta

Download or read book Thin Film Growth of Cuprate and Ruthenate Perovskites and Electronic Characterization of the Electron doped Superconductor Nd 2 x Cex CuO 4 delta written by Solomon Isaac Woods and published by . This book was released on 1998 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Growth and Characterization of Bismuth Perovskite Thin Films for Integrated Magneto optical Isolator Applications

Download or read book Growth and Characterization of Bismuth Perovskite Thin Films for Integrated Magneto optical Isolator Applications written by Alexander R. Taussig and published by . This book was released on 2007 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, we discuss the motivation for integrated magneto-optical isolators and explain why the orthoferrite is such an attractive materials class for this purpose. We then derive from first physical principles the dependence of Faraday rotation, absorption, and certain figures of merit on the material's dielectric tensor elements. Next, we use pulsed laser deposition to grow thin films of BiFeO3 on MgO (001) and SrTiO3 (001) substrates. After optimizing growth conditions to obtain high quality films, we characterize the films' crystal structure with two-dimensional x-ray diffraction. We then examine the magnetic, optical, and magneto-optical properties of these films. We find that the highly textured films grown on SrTiO3 are monoclinic with an out-of-plane c-axis aligned with the (001) direction of the substrate and approximate pseudocubic lattice parameters of a = b = 4.04 A, c = 3.95 A, and 90° - [beta] = -0.88°. These films are weakly magnetic, with a magnetization of 1.2 emu/cm3 at an applied field of 10 kOe; highly absorptive, with an average absorption coefficient of 910 cm-1; and possess a low specific Faraday rotation of 320/cm at 1.8 kOe of applied field. As expected, we find that the magneto-optical figure of merit is negligible for this material due to its high absorption, which we attribute to a thin surface layer of phase separated bismuth and iron oxides caused by bismuth segregation during growth. We offer additional explanations for these values and show the first results of newer, more promising work with mixed cation perovskite.

Book The Controlled Growth of Perovskite Thin Films

Download or read book The Controlled Growth of Perovskite Thin Films written by and published by . This book was released on 1997 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: The broad spectrum of electronic and optical properties exhibited by perovskites offers tremendous opportunities for microelectronic devices, especially when a combination of properties in a single device is desired. Molecular beam epitaxy (MBE) has achieved unparalleled control in the integration of semiconductors at the monolayer-level; its use for the integration of perovskites with similar nanoscale customization appears promising. Composition control and oxidation are often significant challenges to the growth of perovskites by MBE, but we show that these can be met through the use of purified ozone as an oxidant and real-time atomic absorption composition control. The opportunities, challenges, and synthesis of oxide heterostructures by reactive MBE are described, with examples taken from the growth of oxide superconductors and oxide ferroelectrics.

Book Thin Film Growth and Deposition of Functional Perovskite Oxides

Download or read book Thin Film Growth and Deposition of Functional Perovskite Oxides written by Bryce Isaiah Edmondson and published by . This book was released on 2019 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research documented in this work focuses on the growth and deposition of thin film perovskite oxides for their electronic and photonic functionalities. The ever increasing demand for faster electronic devices, particularly in the realm of micro and nanoelectronics, is requiring diversification of the materials used in typical semiconductor-based integrated circuits. Metal oxides, particularly those in the perovskite family of materials, offers a wide range of functionalities that can both increase device performance and add new capabilities such as optical interconnects. The process in which perovskite oxide thin films are deposited and integrated with one another and conventional semiconductors can have many effects on the properties of the resulting device. This work explores these effects in the context of BaTiO3 (BTO) and Ba [subscript x] Sr1- [subscript x] TiO3 (BST) second order nonlinear optical effects, which includes second harmonic generation (SHG) and the linear electro-optic effect (Pockels effect). The work also studies the growth effects on the apparent interfacial conductivity of LaTiO3/SrTiO3 (LTO/STO) heterostructures. BTO thin films grown epitaxially on STO(001) by molecular beam epitaxy (MBE) experience strain relaxation due to misfit dislocations for increasing thickness while epitaxial BST thin films remain strained at equivalent thicknesses due to the smaller lattice mismatch. These strained BST films exhibit larger second harmonic generation than relaxed BTO films, for particular compositions, suggesting that the epitaxial strain enhances their polarization and second order nonlinear susceptibility beyond what is capable in equivalently thick, relaxed BTO films. We also explore the deposition of BTO and BST thin films by a chemical solution method under atmospheric conditions. The films are epitaxial with STO(001) template layers prepared by MBE on Si(001) wafers. Presence of the Pockels effect is confirmed in the films, although optical hysteresis and remanent polarization is not observed owing to the films' small (10-100 nm) grain size, structural defects, and residual tensile stress. Effective Pockels coefficients decrease monotonically with decreasing Ba composition. Non-zero Pockels response is observed in even Sr-rich films, which is explained by the tensile stress that deforms the normally cubic crystal structure into a non-centrosymmetric structure. Post-deposition annealing can increase the Pockels response by approximately four times and is attributed to an increase in grain size and the elimination of structural defects. Finally, we study the effects of oxygen vacancies caused by varying MBE growth conditions of LTO thin films on STO(001) single crystals and thin STO layers on Ge(001). Electrical conductivity of the heterostructures is LTO-thickness dependent, and LTO growth on STO/Ge structures requires orders of magnitude higher partial pressures of molecular oxygen in order to achieve crystalline LTO with proper oxidation states. This is explained by the propensity of LTO to scavenge oxygen from STO during growth, which is limited in LTO/STO/Ge heterostructures, and generates many free carriers and leads to the observed conductivity of the LTO/STO systems

Book Growth and characterization of perovskite thin films

Download or read book Growth and characterization of perovskite thin films written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Growth of Perovskite Oxides on Low cost Substrates by Pulsed Laser Deposition and the Characterization of Their Macroscopic and Microscopic Properties

Download or read book Growth of Perovskite Oxides on Low cost Substrates by Pulsed Laser Deposition and the Characterization of Their Macroscopic and Microscopic Properties written by Marie El Rami and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Different perovskite oxides were grown by pulsed laser deposition on “low-cost” substrates through two different approaches. The first approach involves the use of [Ca2Nb3O10]- nanosheets (NS) as seed layer for the integration of vanadates on amorphous glass substrates. Notably, a global out-of-plane texture of the films, promoted by NS was revealed. The impact of the films thickness on their macroscopic electric-transport properties was investigated using DC transport and spectroscopic ellipsometry measurements. Furthermore, atomic force microscopy coupled to scanning spreading resistance microscopy gives insights to a layer-by-layer growth of SrVO3 (SVO) on NS, a 3D growth on uncovered part with NS, and an onset of crystallization of SVO on glass promoted by thickness. On the other hand, the examined optical properties reveal a transparency improvement when the thickness decreases. These eminent results allow to understand the growth process and the integration of functional oxides on NS, opening up new perspectives to tune the properties of vanadate films as transparent electrodes. The second approach is the combinatorial substrate epitaxy, where a polycrystalline SrTiO3 substrate was synthesized and characterized using macroscopic and local techniques. Similar macroscopic magnetic properties of polycrystalline La0.67Sr0.33MnO3 (LSMO) film were evidenced compared to single crystal substrate. Nevertheless, the submicronic LSMO magnetic properties investigated by magnetic force microscopy and Kerr magnetometry, revealed distinct magnetic response dependent on the grain orientation not observed in the case of single crystal STO substrate. This approach opens new perspectives to establish a library of orientation-functional property relationships in perovskites thin films.