Download or read book Magnetocaloric Effect in Thin Films and Heterostructures written by Christopher Bauer and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The goals of this work are the optimization of the magnetocaloric effect in Gadolinium thin film structures. We approach this issue from two directions, that of process optimization and of interface effects. Past results showed Gd2O3 in our Gadolinium thin films, and the presence of such oxide seemed to grow with the temperature at which the film was grown or annealed. Comparison of samples grown without chamber gettering to those that were gettered show differences in their structural and magnetic properties, and we conclude that gettering is an effective step in enhancing the quality of Gd thin film samples. Early work with Gd/W heterostructures showed a diminished magnetization of the interfacial gadolinium, which reduces the magnetocaloric response as magnetic entropy is proportional to m2/3. It is known that Fe interfaces can boost the Gd moments per atom to above that seen in bulk. As such, we fabricated a series of Fe/Gd heterostructures to study the effects on the structural and magnetic properties of Gd thin films. The use of Fe as a base layer shows increased high frequency oscillations in X-ray reflectivity measurements, indicating sharp interfaces between Gd and Fe. The magnetocaloric measurements produce a magnetic entropy curve with a novel tail extending leftward, making this an improved material over Gd for applications around 240K. All the same, vector magnetometry is needed to ensure that such tail is not due to rotations within the plane and is a direction for further study.

Download or read book Thin Films Based on Gadolinium Applied to the Magnetic Refrigeration written by Asmaa Endichi and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The search for materials with a giant magnetocaloric effect in a massive state and at a temperature close to ambient temperature is of great interest and is mainly obtained by varying the composition of the materials. However, the first-order transition in these materials exhibits considerable thermal hysteresis, making them difficult to handle in applications for refrigerators operating cyclically. Much effort has been made in recent years to reduce this hysteresis, but the performance obtained with these massive materials does not meet the requirements of efficient magnetic refrigeration. Magnetocaloric materials have been largely unexplored on the nanoscale. However, nanostructuring is a well-known and used approach to disrupt the developed structure-property relationships, hence the interest in manufacturing new nanoscale materials. This will improve their magnetic and magnetocaloric characteristics by varying the size and shape. On the other hand, the magnetocaloric effect in magnetic thin layers is particularly interesting for micro-refrigeration. It is therefore important to study the magnetocaloric properties of materials in the form of thin layers in order to eliminate thermal hysteresis. In this sense, few studies have been done to show the potential of thin film materials for magnetic refrigeration and magnetic properties (saturation magnetization, variation of magnetic entropy and relative cooling ratio ...) measured so far limited remains. In this thesis project, we studied metallic gadolinium, which is the preferred choice as a magnetic refrigerant for most prototypes of active magnetic regenerator (AMR) in the form of a thin layer. The magnetocaloric (MCE) and electrocaloric (ECE) properties of the manufactured gadolinium films (Si / Ta / Gd (100 nm) / Pt (3nm)) are measured, in order to obtain more information on the physics behind the interesting electronic and magnetic properties of this material we demonstrate the magneto-caloric effect of the thin film Gd by measuring the electrical transport of the resistance. Thus, during this thesis, the electrical and especially magnetic behaviors of LaCr2Si2C and multiferroics TbMn2O5 are described using the ab-initio method, in order to broaden our understanding of the electronic, magnetic and therefore magnetocaloric characteristics of these compounds based on rare earth. The development of thin layers for magnetic refrigeration was carried out in the materials science research laboratory with the nanomagnetism and spin electronics team at the Jean Lamour Institute in Nancy and the theoretical calculations are made in the material laboratory condensed and interdisciplinary sciences at the Faculty of Sciences of Rabat.

Download or read book Magnetic Interface Effects in Thin Film Heterostructures written by Paul Jan Zakalek and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Magnetism of Complex Oxide Thin Films and Heterostructures written by Jodi Iwata and published by . This book was released on 2012 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies of magnetism at reduced scales have revealed new phenomena that are distinctly different from their bulk counterparts providing insight to the fundamental mechanisms that govern magnetism and other correlated properties. To this end, the use of heteroepitaxy and heterostructures is invaluable for investigating magnetism at reduced dimensions and at surfaces and interfaces. This dissertation is a compilation of investigations examining the magnetic properties of spinel-structure oxide thin films and heterostructures. Of particular interest are non-collinear spin systems as closely competing exchange interactions between magnetic moments give rise to a plethora of ground state degeneracies and phenomena inaccessible in the bulk. The first part of this dissertation highlights the use of heteroepitaxial lattice distortions as a method to tune spin functionality and potentially lift ground state degeneracies more broadly in frustrated magnets. It discusses the first synthesis of heteroepitaxial thin films of the frustrated canted-moment ferrimagnet, CuCr2O4, and demonstrates the modification of exchange interaction strengths which results in greater collinear spin ordering and enhanced magnetization compared to the bulk. The data illustrates the sensitivity of the strong competing exchange interactions suggesting that strain is a promising instrument for perturbing the delicate balance of the exchange interactions in frustrated materials. The second part of this dissertation probes magnetic proximity effects induced by interfaces and unconventional transport properties when CuCr2O4 is incorporated as a barrier layer in magnetic tunnel junctions comprised of ferromagnetic La0.7Sr0.3MnO3 and Fe3O4 electrodes. It is surprising that a heterostructure composed entirely of magnetic materials can achieve distinct magnetic and resistive switching given the complexities present at the two barrier-electrode interfaces. Studies of the CuCr2O4/Fe3O4 interface again illustrate the delicate balance between exchange interactions as proximity effects by Fe3O4 are believed to modulate alignment in the Cr moments. Additionally, the bias dependence of JMR displays a local minimum at zero bias which is believed to be the result of the Fe3O4 band structure and spin filtering properties of the CuCr2O4 barrier.

Download or read book Magnetic Nanostructured Materials written by Ahmed A. El Gendy and published by Elsevier. This book was released on 2018-06-29 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic Nanostructured Materials: From Lab to Fab presents a complete overview of the translation of nanostructured materials into realistic applications, drawing on the most recent research in the field to discuss the fundamentals, synthesis and characterization of nanomagnetics. A wide spectrum of nanomagnetic applications is included, covering industrial, environmental and biomedical fields, and using chemical, physical and biological methods. Materials such as Fe, Co, CoxC, MnGa, GdSi, ferrite nanoparticles and thin films are highlighted, with their potential applications discussed, such as magnetic refrigeration, energy harvesting, magnetic sensors, hyperthermia, MRI, drug delivery, permanent magnets, and data storage devices. Offering interdisciplinary knowledge on the materials science of nanostructured materials and magnetics, this book will be of interest to researchers in materials science, engineering, physics and chemistry with interest in magnetic nanomaterials, as well as postgraduate students and professionals in industry and government. Provides interdisciplinary knowledge on the materials science of nanostructured materials and magnetics Aids in the understanding of complex fundamentals and synthesis methods for magnetic nanomaterials Includes examples of real applications Shows how laboratory work on magnetic nanoparticles connects to industrial implementation and applications

Download or read book The Magnetocaloric Effect and its Applications written by A.M. Tishin and published by CRC Press. This book was released on 2016-04-19 with total page 489 pages. Available in PDF, EPUB and Kindle. Book excerpt: The magnetocaloric effect describes the change in temperature of a magnetic material under adiabatic conditions through the application or removal of an external magnetic field. This effect is particularly pronounced at temperatures and fields corresponding to magnetic phase transitions, and it is a powerful and widely used tool for investigating t

Download or read book Structure and Magnetic Properties of Anisotropic Ferromagnetic Thin film Heterostructures written by Nina-Juliane Steinke and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metallic Amorphous Thin Films and Heterostructures with Tunable Magnetic Properties written by and published by . This book was released on 2015 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fundamentals of Low Dimensional Magnets written by Ram K. Gupta and published by CRC Press. This book was released on 2022-08-29 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: A low-dimensional magnet is a key to the next generation of electronic devices. In some respects, low-dimensional magnets refer to nanomagnets (nanostructured magnets) or single-molecule magnets (molecular nanomagnets). They also include the group of magnetic nanoparticles, which have been widely used in biomedicine, technology, industries, and environmental remediation. Low-dimensional magnetic materials can be used effectively in the future in powerful computers (hard drives, magnetic random-access memory, ultra-low power consumption switches, etc.). The properties of these materials largely depend on the doping level, phase, defects, and morphology. This book covers various nanomagnets and magnetic materials. The basic concepts, various synthetic approaches, characterizations, and mathematical understanding of nanomaterials are provided. Some fundamental applications of 1D, 2D, and 3D materials are covered. This book provides the fundamentals of low-dimensional magnets along with synthesis, theories, structure-property relations, and applications of ferromagnetic nanomaterials. This book broadens our fundamental understanding of ferromagnetism and mechanisms for realization and advancement in devices with improved energy efficiency and high storage capacity.

Download or read book Magnetic Ultra Thin Films Multilayers and Surfaces written by F. Petroff and published by Elsevier. This book was released on 1997-12-18 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Symposium on Magnetic Ultrathin Films, Multilayers and Surfaces, hosted by the European Materials Research Society, was held at the Palais de la Musique et des Congré in Strasbourg, France on June 4-7, 1996. Its central theme was the relationship of magnetic properties and device performance to structure at the nano and micrometer length scale. Research on the magnetism of surfaces, ultrathin films and multilayers has increased dramatically during recent years. This development was triggered by the discovery of coupling between ferromagnetic layers across nonmagnetic spacer layers and of the giant magnetoresistance effect in systems of reduced dimension using various micro and nanofabrication techniques has become a subject of special interest. It is certainly the promising application potential of these effects in new magnetic recording device geometries which causes this intensive research, which is done both by companies and at universities and research institutes. A selection of invited and contributed papers presented at the Symposium and accepted for publication is contained in this volume. The contents of these proceedings are organized into seven sections. A. Nanowires, Nanoparticles, Nanostructuring B. Ultrathin Films and Surfaces, Characterization C. Giant Magnetoresistance D. Coupling, Tunneling E. Growth, Structure, Magnetism F. Growth, Structure, Magnetoresistance G. Coupling, Magnetic processes, Magneto-optics. The first four sections contain invited and oral contributed papers in the listed research domains, while the last three sections contain the contributions presented during three large poster sessions.

Download or read book Multifunctional Oxide Heterostructures written by Evgeny Y. Tsymbal and published by OUP Oxford. This book was released on 2012-08-30 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is devoted to the rapidly developing field of oxide thin-films and heterostructures. Oxide materials combined with atomic-scale precision in a heterostructure exhibit an abundance of macroscopic physical properties involving the strong coupling between the electronic, spin, and structural degrees of freedom, and the interplay between magnetism, ferroelectricity, and conductivity. Recent advances in thin-film deposition and characterization techniques made possible the experimental realization of such oxide heterostructures, promising novel functionalities and device concepts. The book consists of chapters on some of the key innovations in the field over recent years, including strongly correlated oxide heterostructures, magnetoelectric coupling and multiferroic materials, thermoelectric phenomena, and two-dimensional electron gases at oxide interfaces. The book covers the core principles, describes experimental approaches to fabricate and characterize oxide heterostructures, demonstrates new functional properties of these materials, and provides an overview of novel applications.

Download or read book The Magnetoelectric Effect in Oxide Thin Film Heterostructures written by Julian Irwin and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetoelectric materials are poised to make a technological impact in a world where improving efficiency and performance of electronics is increasingly important. That magnetoelectric effect is coupling of electrical and magnetic orderings provided by a single material or several coupled materials. This dissertation explores magnetoelectric effects in two different oxide thin film heterostructures. First, the intrinsic magnetoelectric effect in room temperature multiferroic bismuth ferrite (BiFeO[subscript 3]), and second the extrinsic magnetoelectric effect in strain-coupled composite membranes. Bismuth ferrite is one of the few intrinsically magnetoelectric materials with possible technological importance, as it is ferroelectric and antiferromagnetic at room temperature. Exploiting multiferroic BiFeO[subscript 3] thin films in spintronic devices requires deterministic control of both internal magnetoelectric coupling in BiFeO[subscript 3], as well as exchange coupling of its antiferromagnetic order to a ferromagnetic overlayer. We present an approach using a monodomain magnetoelectric state with single-step switching. Here we demonstrate room temperature, deterministic and robust, exchange coupling between monodomain BiFeO[subscript 3] films and a Co overlayer that is intrinsic (i.e., not dependent on domain walls). Direct coupling between BiFeO[subscript 3] antiferromagnetic order and Co magnetization is observed, with ~ 90[degrees] in-plane Co moment rotation upon single-step switching that is reproducible for hundreds of cycles. Magnetoelectricity in piezoelectric / ferromagnetic thin-film heterostructures comes from piezoelectric strain combined with magnetostriction. In-plane magnetization rotation with an electric field across the film thickness has been challenging due to the large reduction of in-plane piezoelectric strain by substrate clamping, and in two-terminal devices, the requirement of anisotropic in-plane strain. Here we show that these limitations can be overcome two different ways in thin films. First by designing the piezoelectric strain tensor using the boundary interaction between biased and unbiased piezoelectric in (001)-oriented [Pb(Mg[subscript 1/3]Nb[subscript 2/3])O[subscript 3]][subscript 0.7]-[PbTiO[subscript 3]][subscript 0.3] (PMN-PT) membranes with ferromagnetic Ni overlayers, and second by fabricating (011)-oriented Ni/PMN-PT membranes capable of generating anisotropic strain from the symmetry of the crystal alone. We demonstrate several magnetoelectric effects including 90[degrees] rotation of in-plane magnetic anisotropy with a perpendicular electric field. Further optimization of magnetoelectric PMN-PT membrane heterostructures is expected to allow for magnetization rotation at even lower voltages and for nonvolatile magnetoelectric switching.

Download or read book Nanoscale Magnetic Materials and Applications written by J. Ping Liu and published by Springer Science & Business Media. This book was released on 2010-04-05 with total page 731 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoscale Magnetic Materials and Applications covers exciting new developments in the field of advanced magnetic materials. Readers will find valuable reviews of the current experimental and theoretical work on novel magnetic structures, nanocomposite magnets, spintronic materials, domain structure and domain-wall motion, in addition to nanoparticles and patterned magnetic recording media. Cutting-edge applications in the field are described by leading experts from academic and industrial communities. These include new devices based on domain wall motion, magnetic sensors derived from both giant and tunneling magnetoresistance, thin film devices in micro-electromechanical systems, and nanoparticle applications in biomedicine. In addition to providing an introduction to the advances in magnetic materials and applications at the nanoscale, this volume also presents emerging materials and phenomena, such as magnetocaloric and ferromagnetic shape memory materials, which motivate future development in this exciting field. Nanoscale Magnetic Materials and Applications also features a foreword written by Peter Grünberg, recipient of the 2007 Nobel Prize in Physics.

Download or read book Magnetotransport Studies of Complex Oxide Based Thin Films Nanostructures and Heterostructures written by Anil Kumar Rajapitamahuni and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ferroelectric field effect is used to evaluate the contribution of charge to the magnetic properties of LSMO thin films. The polarization field of Pb(Zr,Ti)O 3 (PZT) top gate is used to reversibly modulate the magnetic properties in LSMO thin films. PHE studies of PZT/LSMO heterostructures reveal an enhanced biaxial MCA with the increase of hole doping in LSMO, with the magnitude comparable with that of chemical doping. This study highlights how ferroelectric field effect can be used to independently probe the effects of charge, spin and orbital in MCA with implications in low-power oxide spintronic devices.

Download or read book Magnetic Semiconducting Oxide Thin Films and Heterostructures by Pulsed Laser Deposition written by Gong Wai Leung and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Magnetic and Electronic Phenomena in Oxide Interfaces Thin Films and Heterostructures written by Stephen Barry Porter and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Publications of the National Institute of Standards and Technology Catalog written by National Institute of Standards and Technology (U.S.) and published by . This book was released on 1994 with total page 1162 pages. Available in PDF, EPUB and Kindle. Book excerpt: