Download or read book Field Driven Domain Wall Dynamics in Ferromagnetic Nanostripes written by Sascha Glathe and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: I report on the dynamics of magnetic domain walls (DW) in ferromagnetic nanostripes. The investigations were carried out using the giant magnetoresistance effect, while the DW moved in a soft magnetic NiFe layer. This technique enabled me to verify for the first time the so called Walker Breakdown process in single shot measurements. Additionally I investigated the influence of an in plane transverse field (perpendicular to the movement direction of the DW) on the DW dynamics. It turned out that the DW mobility can be significantly increased, because of a change of the DW shape due to the effect of the transverse field. In the course of the single shot experiments I discovered a new kind of DW motion. Under the influence of a transverse field or in comparably wide nanostripes the DW is stretched along its movement direction. This longitudinal elongated DW is only dynamically stable and is a result of the interplay between the exchange energy and the demagnetization energy. The influence of the nanostripe real shape, in particular the shape of the cross section, on the DW behavior was investigated in another part of this thesis. It turned out that one finds different so called critical Walker fields in the same sample. This critical field depends theoretically on geometric and material parameters and thus should be the same for one sample. I could explain these findings with different stray field contribution in the region of the DW in dependence on the magnetization configuration inside the wall. In a last part I investigated the influence of a transverse field on the DW pinning process. Due to geometric imperfections of the nanostripe, e.g. edge roughness, the DW can be pinned to such a defect. I showed that a transverse field decreases the pinning probability of weak pinning sides. However, for strong pinning sites the probability can show complicated dependencies on the DW pinning process.
Download or read book Magnetic Domain Walls Driven by Interfacial Phenomena written by Satoru Emori and published by . This book was released on 2014 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: A domain wall in a ferromagnetic material is a boundary between differently magnetized regions, and its motion provides a convenient scheme to control the magnetization state of the material. Domain walls can be confined and moved along nanostrips of magnetic thin films, which are proposed platforms for next generations of solid-state magnetic memory-storage and logic devices. In these devices, domain walls must be moved by electric current, rather than by magnetic field, to achieve scalability and lower-power operation. Recent studies have reported efficient domain-wall motion driven by current in out-of-plane magnetized multilayer films with strong spin-orbit coupling. In particular, extraordinary current-driven domain-wall motion has been observed in atomically-thin ferromagnets sandwiched between a nonmagnetic heavy metal and an insulator. Through experimental studies on various sputtered magnetic multilayers, we elucidate the mechanism of such anomalous domain-wall dynamics. We show that conventional current-induced spin-transfer torques, which drive domain walls in thicker films, are negligible in ultrathin ferromagnets. We also show that the Rashba field, often reported in materials with strong spin-orbit coupling, does not contribute to the observed efficient domain-wall motion. The anomalous dynamics instead emerges from the spin Hall effect: a charge current in the nonmagnetic heavy metal generates a spin current, which exerts a torque on spins in the adjacent ferromagnet. This spin Hall torque drives domain walls forward if the domain-wall spins are parallel to the nanostrip axis with a fixed chirality. We reveal that the Dzyaloshinskii-Moriya interaction, arising from spin-orbit coupling and asymmetric interfaces, stabilizes homochiral domain walls in ultrathin ferromagnets. Our findings not only provide a route to bolster current-driven domain-wall dynamics, but also enable new chiral magnetic textures in magnetic heterostructures for device applications.
Download or read book Nanomagnetism and Spintronics written by André Thiaville and published by Elsevier Inc. Chapters. This book was released on 2013-10-07 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spin-transfer torque manifests itself in two main geometries, either submicrometer diameter pillars composed of magnetic multilayers, flooded by a current perpendicular to plane (CPP), or nanowires with current flowing in their plane (CIP). The first situation can be described rather well, from the magnetic point of view, in the framework of the macrospin model (see by Y. Suzuki). In the latter case, the typical situation is that of a magnetic domain wall under CIP current, with many internal degrees of freedom. In by H. Kohno and G. Tatara, a simplest model of the domain wall, called collective coordinates model, has been introduced to study this question. In this chapter, we will address the entire manifold of the degrees of freedom in the domain wall by micromagnetic numerical simulations, and apply this to the physics of CIP spin transfer in magnetic domain walls. We will consider soft magnetic materials only, where domain wall structures and dynamics are controlled by magnetostatics. This corresponds to the largest part of experiments that have been performed up to now, soft magnetic materials having generally lower coercive forces and domain wall propagation fields. The experimental counterpart to this chapter can be found in , by T. Ono and T. Shinjo. After briefly introducing micromagnetics and the typology of domain walls in samples shaped into nanostrips, we start by reviewing the field-driven dynamics in such samples. This situation was indeed considered first, historically, and led to the introduction of several useful concepts. Prominent among them are the separation between steady-state and precessional regimes, and the existence of a maximum velocity for a domain wall. The spin-transfer torque-induced domain wall dynamics will then be addressed, considering first the implementation of the CIP spin transfer torque in micromagnetics, with several components as introduced by theory. Comparison will be made to the field-driven case, with similarities and differences highlighted. In the nascent field of nanomagnetism and spintronics, micromagnetics can be considered to play the role of a translator. There are on one side experiments and on the other side theories about interaction between magnetization and spin-polarized electrical currents. Micromagnetics is a tool that translates the equations of the latter into quantitative predictions that can be compared to the former. Considering the present state of the subject of this book, with rapidly advancing experiments and theories, keeping in touch those two aspects of research is very important for its sound development. This is the objective of this chapter.
Download or read book Current driven Domain Wall Dynamics and Its Electric Signature in Ferromagnetic Nanowires written by Yang Liu and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We study current-induced domain wall dynamics in a thin ferromagnetic nanowire. We derive the effective equations of domain wall motion, which depend on the wire geometry and material parameters. We describe the procedure to determine these parameters by all-electric measurements of the time-dependent voltage induced by the domain wall motion. We provide an analytical expression for the time variation of this voltage. Furthermore, we show that the measurement of the proposed effects is within reach with current experimental techniques. We also show that a certain resonant time-dependent current moving a domain wall can significantly reduce the Joule heating in the wire, and thus it can lead to a novel proposal for the most energy efficient memory devices. We discuss how Gilbert damping, non-adiabatic spin transfer torque, and the presence of Dzyaloshinskii-Moriya interaction can effect this power optimization. Furthermore, we propose a new nanodot magnetic device. We derive a specific time-dependent current that is needed to switch the magnetization of the nanodot the most efficiently.
Download or read book Nanomagnetism and Spintronics written by Teruo Ono and published by Elsevier Inc. Chapters. This book was released on 2013-10-07 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamical behavior of magnetic domain wall (DW) is one of the main issues in the field of spintronics. In this chapter, several experimental studies in DW dynamics in nanomagnetic systems are described. For the study of DW motion in nanoscale wires, samples with a trilayer structure, ferromagnetic/nonmagnetic/ferromagnetic, were prepared and the position of DW was estimated from electrical resistance measurements using giant magnetoresistance principle. The velocity of DW driven by an external field has been evaluated from the resistance change. On the other hand, current-driven DW motion in a single wire of ferromagnetic layer was studied by magnetic force microscopy (MFM). All-electrical control and local detection of multiple magnetic DWs are also shown. Magnetic vortex structures are realized in nanoscale ferromagnetic dot systems. The behavior of vortex core magnetization was observed by MFM. Recent topics such as the switching of vortex core driven by a high frequency AC are introduced. Furthermore, all-electrical operation of a magnetic vortex core memory cell is demonstrated.
Download or read book Ferromagnetodynamics written by Thomas Henry O'Dell and published by John Wiley & Sons. This book was released on 1981 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Current induced Domain wall Dynamics in Ferromagnetic Nanowires written by Benjamin Krüger and published by . This book was released on 2006 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Domain Wall Dynamics in Ferromagnetic Nanowires written by Badriya Ahmad AL-Rashdiyah and published by . This book was released on 2016 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Static Spin Distributions and Dynamics of Magnetic Domain Walls in Soft Magnetic Nanostructures written by Jusang Yang and published by . This book was released on 2013 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: The static and dynamic properties of spin distributions within domain walls(DWs) confined by Permalloy nanowire conduits are investigated by numerical simulations and high-speed magneto-optic polarimetry. Phase boundaries and critical points associated with DW spin distributions of various topologies are accurately determined using high-performance computing resources. Field-driven mobility curves that characterize DW propagation velocities in 20 nm thick nanowires are calculated with increasing the width of nanowires. Beyond the simple one-dimensional solution, the simulations reveal the four distinct dynamic modes. Oscillations of the field-driven DW velocity in Permalloy nanowires are observed above the Walker breakdown condition using high-speed magneto-optic polarimetry. A one-dimensional analytical model and numerical simulations of DW motion and spin dynamics are used to interpret the experimental data. Velocity oscillations are shown to be much more sensitive to properties of the DW guide structure (which also affect DW mobility) than the DW spin precessional frequency, which is a local property of the material. Transverse bias field effects on field-driven DW velocity are studied experimentally and numerically. DW velocities and spin configurations are determined as functions of longitudinal drive field, transverse bias field, and nanowire width. For a nanowire that supports vortex wall structures, factor of ten enhancements of the DW velocity are observed above the critical longitudinal drive-field (that marks the onset of oscillatory DW motion) when a transverse bias field is applied. The bias-field enhancement of DW velocity is explained by numerical simulations of the spin distribution and dynamics within a propagating DW that reveal dynamic stabilization of coupled vortex structures and suppression of oscillatory motion in the nanowire conduit resulting in uniform DW motion at high speed. Current-driven and current-assisted field-driven domain wall dynamics in ferromagnetic nanowires have thermal effects resulting from Joule heating, which make difficult to separate the spin-torque effects on DW displacements. To understand the thermal effects on DW dynamics, the temperature dependence of field-driven DW velocity is explored using high-bandwidth scanning Kerr polarimetry. Walker critical fields are decreased with increasing temperature and temperature-induced dynamic mode changes are observed. The results show that Joule heating effects are playing an important role in current-driven/current-assisted field-driven DW dynamics.
Download or read book Magnetic Domain Wall Dynamics in the Presence of an In plane Field written by Kadri L. Vural and published by . This book was released on 1980 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Field Driven Vortex Domain Wall Motion in Magnetic Nanostructures written by Tobias Weindler and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physical Properties of Nanorods written by Roman Krahne and published by Springer Science & Business Media. This book was released on 2013-06-12 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inorganic nanoparticles are among the most investigated objects nowadays, both in fundamental science and in various technical applications. In this book the physical properties of nanowires formed by nanoparticles with elongated shape, i.e. rod-like or wire-like, are described. The transition in the physical properties is analyzed for nanorods and nanowires consisting of spherical and rod-like nanoparticles. The physical properties of nanowires and elongated inorganic nanoparticles are reviewed too. The optical, electrical, magnetic, mechanical and catalytic properties of nanowires consisting of semiconductors, noble and various other metals, metal oxides properties and metal alloys are presented. The applications of nanorods and nanowires are discussed in the book.
Download or read book Magnetism of Surfaces Interfaces and Nanoscale Materials written by Robert E. Camley and published by Elsevier. This book was released on 2015-10-27 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past 30 years, magnetic research has been dominated by the question of how surfaces and interfaces influence the magnetic and transport properties of nanostructures, thin films and multilayers. The research has been particularly important in the magnetic recording industry where the giant magnetoresistance effect led to a new generation of storage devices including hand-held memories such as those found in the ipod. More recently, transfer of spin angular momentum across interfaces has opened a new field for high frequency applications.This book gives a comprehensive view of research at the forefront of these fields. The frontier is expanding through dynamic exchange between theory and experiment. Contributions have been chosen to reflect this, giving the reader a unified overview of the topic. Addresses both theory and experiment that are vital for gaining an essential understanding of topics at the interface between magnetism and materials science Chapters written by experts provide great insights into complex material Discusses fundamental background material and state-of-the-art applications, serving as an indispensable guide for students and professionals at all levels of expertise Stresses interdisciplinary aspects of the field, including physics, chemistry, nanocharacterization, and materials science Combines basic materials with applications, thus widening the scope of the book and its readership
Download or read book Recent Advances in Topological Ferroics and their Dynamics written by Robert L. Stamps and published by Academic Press. This book was released on 2019-10-18 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent Advances in Topological Ferroics and Their Dynamics, Volume 70 in the Solid State Physics series, provides the latest information on the branch of physics that is primarily devoted to the study of matter in its solid phase, especially at the atomic level. This prestigious serial presents timely and state-of-the-art reviews pertaining to all aspects of solid state physics. Contains contributions from leading authorities in the study of solid state physics, especially at the atomic level Informs and updates on all the latest developments in the field Presents timely, state-of-the-art reviews pertaining to all aspects of solid state physics
Download or read book Mathematical Modelling and Scientific Computing with Applications written by Santanu Manna and published by Springer Nature. This book was released on 2020-02-14 with total page 467 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains original research papers presented at the International Conference on Mathematical Modelling and Scientific Computing, held at the Indian Institute of Technology Indore, India, on 19–21 July 2018. Organized into 30 chapters, the book presents the recent progress and the most advanced innovations, trends, and real-world challenges encountered and solutions embraced in the applications of mathematics and scientific computing. The book will be of interests to a wide variety of researchers, students and the practicing engineers working in diverse areas of science and engineering, ranging from applied and computational mathematics, vibration problem, computer science, and numerical optimization to physics, chemistry, biology, electrical, civil, mechanical, chemical, seismology, aerospace, and medical sciences. The aim of the conference is to bring together leading academicians, scientists, researchers, engineers, and industry partners from all over the globe to exchange and share their experiences and research results on various aspects of applied mathematics and scientific computation, like, differential equation, modeling, simulation, dynamical systems, numerical analysis, matrix theory, inverse problems, and solid and fluid mechanics, computational engineering.
Download or read book Magnetic Domain Wall Dynamics and Pulsed Magnetization Reversal in Four Soft Ferromagnetic Alloys written by Peter Williams and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Micromagnetics of Domains and Walls in Soft Ferromagnetic Materials written by Samuel Wonder Yuan and published by . This book was released on 1992 with total page 728 pages. Available in PDF, EPUB and Kindle. Book excerpt:
