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Author: Brooke Lu Mesler Publisher: ISBN: Category : Languages : en Pages : 136
Book Description
Understanding and controlling the manipulation of spin structures on a nanometer length scale is of primary importance to contemporary scientific investigations and future technological applications of magnetic materials. Soft x-ray transmission microscopy offers imaging with a spatial resolution down to 10 nm, and a temporal resolution of about 70 psec, with element specific magnetic contrast. As such, it is an ideal method for studying fast nanoscale spin dynamics. The focus of this dissertation is on imaging the response of magnetic vortex cores to external applied fields using soft x-ray transmission microscopy. A technique for pinpointing vortex dynamics without time resolution was used to survey the response of a vortex core to RF fields of varying frequency and amplitude. This investigation revealed an unexpected nonlinear response of the vortex core at higher amplitude driving frequencies. Time-resolved images of the vortex core response in the linear regime were taken using a technique which phase-locked the RF driving field to the x-ray imaging pulses. These experimental images probing the frequency response of the vortex core motion are the initial step towards a deeper understanding of the behavior of the vortex core when driven by magnetic fields with frequencies near its resonant frequency. In addition to investigating the dynamic response of a single vortex core, a magnetic system with two interacting vortex cores was studied. A patterned rectangular magnetic sample with a 7-domain magnetization configuration and two vortex cores at remanence was used in this experiment. The magnetization of this sample was imaged after the application of a fast magnetic field pulse using a pump-probe time-resolved imaging technique. The images taken showed a distortion of the vortex cores after the pulse was applied, and combined with simulation, these results provide strong evidence for the creation and annihilation of vortex-antivortex core pairs during the excitation of the initial vortices. This lends support to the many theories suggesting that a vortex-antivortex core pair is created and annihilated during the switching of vortex core polarity. The studies outlined in this dissertation demonstrate the strength of transmission soft x-ray microscopy as a tool for investigating spin dynamics.
Author: Brooke Lu Mesler Publisher: ISBN: Category : Languages : en Pages : 136
Book Description
Understanding and controlling the manipulation of spin structures on a nanometer length scale is of primary importance to contemporary scientific investigations and future technological applications of magnetic materials. Soft x-ray transmission microscopy offers imaging with a spatial resolution down to 10 nm, and a temporal resolution of about 70 psec, with element specific magnetic contrast. As such, it is an ideal method for studying fast nanoscale spin dynamics. The focus of this dissertation is on imaging the response of magnetic vortex cores to external applied fields using soft x-ray transmission microscopy. A technique for pinpointing vortex dynamics without time resolution was used to survey the response of a vortex core to RF fields of varying frequency and amplitude. This investigation revealed an unexpected nonlinear response of the vortex core at higher amplitude driving frequencies. Time-resolved images of the vortex core response in the linear regime were taken using a technique which phase-locked the RF driving field to the x-ray imaging pulses. These experimental images probing the frequency response of the vortex core motion are the initial step towards a deeper understanding of the behavior of the vortex core when driven by magnetic fields with frequencies near its resonant frequency. In addition to investigating the dynamic response of a single vortex core, a magnetic system with two interacting vortex cores was studied. A patterned rectangular magnetic sample with a 7-domain magnetization configuration and two vortex cores at remanence was used in this experiment. The magnetization of this sample was imaged after the application of a fast magnetic field pulse using a pump-probe time-resolved imaging technique. The images taken showed a distortion of the vortex cores after the pulse was applied, and combined with simulation, these results provide strong evidence for the creation and annihilation of vortex-antivortex core pairs during the excitation of the initial vortices. This lends support to the many theories suggesting that a vortex-antivortex core pair is created and annihilated during the switching of vortex core polarity. The studies outlined in this dissertation demonstrate the strength of transmission soft x-ray microscopy as a tool for investigating spin dynamics.
Author: Burkard Hillebrands Publisher: Springer Science & Business Media ISBN: 3540460977 Category : Science Languages : en Pages : 343
Book Description
This second volume of the book on spin dynamics in confined magnetic structures covers central aspects of spin dynamic phenomena, so that researchers can find a comprehensive compilation of the current work in the field. Introductory chapters help newcomers to understand the basic concepts, and the more advanced chapters give the current state of the art for most spin dynamic issues in the milliseconds to femtoseconds range. Both experimental techniques and theoretical work are discussed. The comprehensive presentation of these developments makes this volume very timely and valuable for every researcher working in the field of magnetism. It describes the new experimental techniques which have advanced this field very rapidly. Among the techniques covered, particular attention is given to those involving high temporal, elemental and spatial resolution as well as to techniques involving magnetic field pulses with very short rise times and durations.
Author: Chunhui Du Publisher: ISBN: Category : Languages : en Pages : 137
Book Description
Generation and manipulation of spin is of central importance in modern physics. This intense interest is driven in part by exciting new phenomena in spintronics such as spin Hall effects and spin transfer torque as well as by the growth in new tools enabling microscopic studies. Ferromagnetic resonance (FMR) is a powerful technique to study macro-scale spin ensembles, and an effective method to generate pure spin currents. Combined with scanning capability, it can be used as a spin sensitive microscopy with nano-scale spatial resolution to bring fresh insights in spintronics and achieve local excitation, manipulation, and detection of spin. In the first part of this thesis, I will briefly introduce the field of spintronics. In the second chapter, I demonstrate the use of FMR spectroscopy to study the static and dynamics properties of novel materials. In the third chapter, I present the FMR spin pumping technique in ferromagnetic material/normal metal bilayer to characterize the spin Hall angles for a series of 3d, 4d, and 5d transition metals with widely varying spin-orbit coupling strengths and demonstrate that both atomic number, Z, and d electron count play important roles in spin Hall physics. Those work studies the spin dynamics and transport across the interface defined by material discontinuity in macro-scale sample. To study nano-scale structures, in the forth and fifth chapters, I describe probing and imaging spin dynamics using spin wave modes confined into microscopic volumes in a ferromagnetic film by the spatially inhomogeneous magnetic field of a scanned micromagnetic tip of a ferromagnetic resonance force microscope (FMRFM). It shows the characteristics of the localized mode can be broadly tuned by appropriate selection of the orientation of the tip moment relative to the applied uniform field. Micromagnetic simulations accurately reproduce our experimental results and allow quantitative understanding of the ferromagnetic resonance force microscopy spectra. These results provide a universal method of generating and understanding the tightly confined localized modes in various measurement geometries and material systems with increased freedom in the choice of tip and material, and paves the way to improved spatial resolution for imaging using localized spin wave modes. At last, I demonstrate a design of room temperature FMR force microscope with both imaging and transport capability to study and image spin dynamics and transport across the interface defined by the magnetic textures with nano-scale resolution. The sixth chapter is a conclusion of the entire dissertation.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The spin of the electron and its associated magnetic moment marks the basic unit for magnetic properties of matter. Magnetism, in particular ferromagnetism and antiferromagnetism is described by a collective order of these spins, where the interaction between individual spins reflects a competition between exchange, anisotropy and dipolar energy terms. As a result the energetically favored ground state of a ferromagnetic system is a rather complex spin configuration, the magnetic domain structure. Magnetism is one of the eldest scientific phenomena, yet it is one of the most powerful and versatile utilized physical effects in modern technologies, such as in magnetic storage and sensor devices. To achieve highest storage density, the relevant length scales, such as the bit size in disk drives is now approaching the nanoscale and as such further developments have to deal with nanoscience phenomena. Advanced characterization tools are required to fully understand the underlying physical principles. Magnetic microscopes using polarized soft X-rays offer a close-up view into magnetism with unique features, these include elemental sensitivity due to X-ray magnetic dichroism effects as contrast mechanism, high spatial resolution provided by state-of-the-art X-ray optics and fast time resolution limited by the inherent time structure of current X-ray sources, which will be overcome with the introduction of ultrafast and high brilliant X-ray sources.
Author: Burkard Hillebrands Publisher: Springer ISBN: 9783642448263 Category : Science Languages : en Pages : 0
Book Description
The third volume of this book addresses central aspects of spin-dynamic phenomena on a tutorial level. This volume concentrates on new experimental techniques such as ferromagnetic-resonance-force microscopy and two-photon photoemission. There is a chapter devoted to the hot subject of spin-transfer torque. The comprehensive presentation makes this a timely and valuable resource for every researcher working in the field of magnetism.
Author: Tim Salditt Publisher: Springer Nature ISBN: 3030344134 Category : Science Languages : en Pages : 634
Book Description
This open access book, edited and authored by a team of world-leading researchers, provides a broad overview of advanced photonic methods for nanoscale visualization, as well as describing a range of fascinating in-depth studies. Introductory chapters cover the most relevant physics and basic methods that young researchers need to master in order to work effectively in the field of nanoscale photonic imaging, from physical first principles, to instrumentation, to mathematical foundations of imaging and data analysis. Subsequent chapters demonstrate how these cutting edge methods are applied to a variety of systems, including complex fluids and biomolecular systems, for visualizing their structure and dynamics, in space and on timescales extending over many orders of magnitude down to the femtosecond range. Progress in nanoscale photonic imaging in Göttingen has been the sum total of more than a decade of work by a wide range of scientists and mathematicians across disciplines, working together in a vibrant collaboration of a kind rarely matched. This volume presents the highlights of their research achievements and serves as a record of the unique and remarkable constellation of contributors, as well as looking ahead at the future prospects in this field. It will serve not only as a useful reference for experienced researchers but also as a valuable point of entry for newcomers.
Author: National Research Council Publisher: National Academies Press ISBN: 030916463X Category : Science Languages : en Pages : 222
Book Description
Scientists and engineers have long relied on the power of imaging techniques to help see objects invisible to the naked eye, and thus, to advance scientific knowledge. These experts are constantly pushing the limits of technology in pursuit of chemical imagingâ€"the ability to visualize molecular structures and chemical composition in time and space as actual events unfoldâ€"from the smallest dimension of a biological system to the widest expanse of a distant galaxy. Chemical imaging has a variety of applications for almost every facet of our daily lives, ranging from medical diagnosis and treatment to the study and design of material properties in new products. In addition to highlighting advances in chemical imaging that could have the greatest impact on critical problems in science and technology, Visualizing Chemistry reviews the current state of chemical imaging technology, identifies promising future developments and their applications, and suggests a research and educational agenda to enable breakthrough improvements.
Author: John J. Kasianowicz Publisher: Springer Science & Business Media ISBN: 9781402006975 Category : Science Languages : en Pages : 46
Book Description
Polymers are essential to biology because they can have enough stable degrees of freedom to store the molecular code of heredity and to express the sequences needed to manufacture new molecules. Through these they perform or control virtually every function in life. Although some biopolymers are created and spend their entire career in the relatively large free space inside cells or organelles, many biopolymers must migrate through a narrow passageway to get to their targeted destination. This suggests the questions: How does confining a polymer affect its behavior and function? What does that tell us about the interactions between the monomers that comprise the polymer and the molecules that confine it? Can we design and build devices that mimic the functions of these nanoscale systems? The NATO Advanced Research Workshop brought together for four days in Bikal, Hungary over forty experts in experimental and theoretical biophysics, molecular biology, biophysical chemistry, and biochemistry interested in these questions. Their papers collected in this book provide insight on biological processes involving confinement and form a basis for new biotechnological applications using polymers. In his paper Edmund DiMarzio asks: What is so special about polymers? Why are polymers so prevalent in living things? The chemist says the reason is that a protein made of N amino acids can have any of 20 different kinds at each position along the chain, resulting in 20 N different polymers, and that the complexity of life lies in this variety.
Author: Hari Singh Nalwa Publisher: ISBN: 9781588830005 Category : Science Languages : en Pages : 0
Book Description
Twelve contributions comprise a reference source that is a coherent presentation of the state of the art in this fast growing area of nanotechnology research. Magnetic nanostructures are important for their phenomenal potential for storage; their great commercial value will come from applications in
Author: Brooke Lu Mesler
Author: Brooke Lu Mesler
Author: Burkard Hillebrands
Author: Chunhui Du
Author: 
Author: Burkard Hillebrands
Author: Nanna Zhou Hagström
Author: Tim Salditt
Author: National Research Council
Author: John J. Kasianowicz
Author: Hari Singh Nalwa