Download or read book Ultrafast Manipulation of Magnetic Order with Electrical Pulses written by Yang Yang and published by . This book was released on 2005 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the last 30 years spintronics has been a very rapidly expanding field leading to lots of new interesting physics and applications. As with most technology-oriented fields, spintronics strives to control devices with very low energy consumption and high speed. The combination of spin and electronics inherent to spintronics directly tackles energy efficiency, due to the non-volatility of magnetism. However, speed of operation of spintronic devices is still rather limited (~nanoseconds), due to slow magnetization precessional frequencies. Ultrafast magnetism (or opto-magnetism) is a relatively new field that has been very active in the last 20 years. The main idea is that intense femtosecond laser pulses can be used in order to manipulate the magnetization at very fast time-scales (~100 femtoseconds). However, the use of femtosecond lasers poses great application challenges such as diffraction limited optical spot sizes which hinders device density, and bulky and expensive integration of femtosecond lasers into devices. In this thesis, our efforts to combine ultrafast magnetism and spintronics are presented. First, we show that the magnetization of ferrimagnetic GdFeCo films can be switched by picosecond electronic heat current pulses. This result shows that a non-thermal distribution of electrons directly excited by laser is not necessary for inducing ultrafast magnetic dynamics. Then, we fabricate photoconductive switch devices on a LT-GaAs substrate, to generate picosecond electrical pulses. Intense electrical pulses with 10ps (FWHM) duration and peak current up to 3A can be generated and delivered into magnetic films. Distinct magnetic dynamics in CoPt films are found between direct optical heating and electrical heating. More importantly, by delivering picosecond electrical pulses into GdFeCo films, we are able to deterministically reverse the magnetization of GdFeCo within ~10ps. This is more than one order of magnitude faster than any other electrically controlled magnetic switching. Our results present a fundamentally new switching mechanism electrically, without requirement for any spin polarized current or spin transfer/orbit torques. Our discovery that ultrafast magnetization switching can be achieved with electrical pulses will launch a new frontier of spintronics science and herald a new generation of spintronic devices that operate at high speed with low energy consumption. At last, to push ultrafast spintronics to practical use, ultrafast switching of a ferromagnetic film is desired. By exploiting the exchange interaction between GdFeCo and ferromagnetic Co/Pt layer, we achieved ultrafast (sub 10ps) switching of ferromagnetic film with a single laser pulse. This result will open up the possibility to control ferromagnetic materials at ultrafast time scale, critical for practical applications.

Download or read book Ultrafast Manipulation of Magnetization Using On chip THz written by Kaushalya and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The need for memory storage devices has skyrocketed over the last few decades especially after the development of the internet. This need has reached enormous heights in the past two years, soon after the pandemic due to COVID-19. Hard disk drives (HDDs) are known to have the potential to meet up with the high-density data storage demands. This thesis deals with one of the major challenges faced within the spintronic community to improve the speed and the energy consumption of memory devices.The speed of operation during the writing of a magnetic bit depends on the magnetization switching mechanism employed. The switching mechanism is itself dependent on the intrinsic magnetic properties of the sample and the externally induced excitation that drives the reversal of the magnetic bit 1. In this thesis, we will focus on the use of spin-orbit torque (SOT) excitations to drive the reversal, which is a relatively new but fast and energy-efficient approach in comparison with other state-of-the-art methods.The typical speed of magnetization reversal using SOTs is in the range of few nanoseconds, far slower than the picosecond-long switching that is possible with charge-based memory devices2. In fact, a record reversal speed with electrical pulses as short as ~200ps was reported by Garello et. al., 3 in 2011 using SOTs. This thesis reports further efforts to speed up the magnetization reversal by almost 2 orders of magnitude by exploiting such SOTs. To this aim, THz electrical pulses were generated via the use Auston photoconductive switches. We demonstrate that a single 6ps wide electrical pulse can induce a SOT to a 1nm thin Co ferromagnetic layer and result in a full magnetization reversal. A systematic study to understand SOTs in the picosecond time regime is also undertaken via using different magnetic nanostructures.In magnetic memory devices, a “read-head” is used to read the stored information in the device. Typically, in spintronic devices, giant magnetoresistance (GMR) or tunnel magnetoresistance (TMR) based read heads are used for such operations. In this thesis, we also report on the attempts of developing a GMR sensor working in the THz regime.To undertake the aforementioned studies, a pump-probe optical and optoelectrical experimental setup has also been built and a detailed report of the same is also provided in the thesis.

Download or read book Ultrafast Magnetism I written by Jean-Yves Bigot and published by Springer. This book was released on 2014-08-05 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume on Ultrafast Magnetism is a collection of articles presented at the international “Ultrafast Magnetization Conference” held at the Congress Center in Strasbourg, France, from October 28th to November 1st, 2013. This first conference, which is intended to be held every two years, received a wonderful attendance and gathered scientists from 27 countries in the field of Femtomagnetism, encompassing many theoretical and experimental research subjects related to the spins dynamics in bulk or nanostructured materials. The participants appreciated this unique opportunity for discussing new ideas and debating on various physical interpretations of the reported phenomena. The format of a single session with many oral contributions as well as extensive time for poster presentations allowed researchers to have a detailed overview of the field. Importantly, one could sense that, in addition to studying fundamental magnetic phenomena, ultrafast magnetism has entered in a phase where applied physics and engineering are playing an important role. Several devices are being proposed with exciting R&D perspectives in the near future, in particular for magnetic recording, time resolved magnetic imaging and spin polarized transport, therefore establishing connections between various aspects of modern magnetism. Simultaneously, the diversity of techniques and experimental configurations has flourished during the past years, employing in particular Xrays, visible, infra-red and terahertz radiations. It was also obvious that an important effort is being made for tracking the dynamics of spins and magnetic domains at the nanometer scale, opening the pathway to exciting future developments. The concerted efforts between theoretical and experimental approaches for explaining the dynamical behaviors of angular momentum and energy levels, on different classes of magnetic materials, are worth pointing out. Finally it was unanimously recognized that the quality of the scientific oral and poster presentations contributed to bring the conference to a very high international standard.

Download or read book Introduction to Ultrafast Phenomena written by Guo-ping Zhang and published by CRC Press. This book was released on 2020-12-08 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book, the first of this kind, provides a comprehensive introduction to ultrafast phenomena, covering the fundamentals of ultrafast spin and charge dynamics, femtosecond magnetism, all-optical spin switching, and high-harmonic generation. It covers the experimental tools, including ultrafast pump-probe experiments, and theoretical methods including quantum chemistry and density functional theory, both time-independent and time-dependent. The authors explain in clear language how an ultrafast laser pulse is generated experimentally, how it can induce rapid responses in electrons and spins in molecules, nanostructures and solids (magnetic materials and superconductors), and how it can create high-harmonic generation from atoms and solids on the attosecond timescale. They also show how this field is driving the next generation of magnetic storage devices through femtomagnetism, all-optical spin switching in ferrimagnets and beyond, magnetic logic in magnetic molecules, and ultrafast intense light sources, incorporating numerous computer programs, examples, and problems throughout, to show how the beautiful research can be done behind the scene. Key features: · Provides a clear introduction to modern ultrafast phenomena and their applications in physics, chemistry, materials sciences, and engineering. · Presents in detail how high-harmonic generation occurs in atoms and solids. · Explains ultrafast demagnetization and spin switching, a new frontier for development of faster magnetic storage devices. · Includes numerous worked-out examples and problems in each chapter, with real research codes in density functional theory and quantum chemical calculations provided in the chapters and in the Appendices. This book is intended for undergraduate and graduate students, researchers in physics, chemistry, biology, materials sciences, and engineering.

Download or read book Coherent Phenomena in Molecular Physics written by Tamar Seideman and published by Frontiers Media SA. This book was released on 2022-08-09 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser Physics and Technology written by Pradeep Kumar Gupta and published by Springer. This book was released on 2014-11-06 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book, ‘Laser Physics and Technology’, addresses fundamentals of laser physics, representative laser systems and techniques, and some important applications of lasers. The present volume is a collection of articles based on some of the lectures delivered at the School on ‘Laser Physics and Technology’ organized at Raja Ramanna Centre for Advanced Technology during March, 12-30, 2012. The objective of the School was to provide an in-depth knowledge of the important aspects of laser physics and technology to doctoral students and young researchers and motivate them for further work in this area. In keeping with this objective, the fourteen chapters, written by leading Indian experts, based on the lectures delivered by them at the School, provide along with class room type coverage of the fundamentals of the field, a brief review of the current status of the field. The book will be useful for doctoral students and young scientists who are embarking on a research in this area as well as to professionals who would be interested in knowing the current state of the field particularly in Indian context.

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 Observation and Control of Magnetic Order Dynamics by Terahertz Magnetic Nearfield written by Takayuki Kurihara and published by Springer Nature. This book was released on 2022-01-09 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explicates the optical controls of antiferromagnetic spins by intense terahertz (THz) electromagnetic waves. The book comprises two key components: (1) the experimental demonstration of the enhancement of a THz magnetic field using a split-ring resonator (SRR) and (2) the control of the direction of magnetization by using the enhanced THz magnetic field to break the symmetry of optically-induced phase transition. These make up the first step leading to future spintronics devices. In the beginning of the book, the author reviews the basics of the ultrafast laser and nonlinear optical techniques as well as the previously achieved experiments to control spin dynamics by THz magnetic fields. In this context, a new experimental protocol is described, in which electron spins in a ferromagnetic material are redirected at the unprecedented level in cooperation with the enhanced THz magnetic field. Subsequently, the author demonstrates that the THz magnetic field is significantly amplified as a nearfield around the SRR structured metamaterial, which is implemented by measuring spin precession in a solid. At the end, the author presents the key experiment in which the amplified THz magnetic nearfield is applied to the weak ferromagnet ErFeO3 along with the femtosecond near-infrared pulse, demonstrating the successful control of symmetry breaking of the spin system due to coherent control of the optically-induced spin reorientation phase transition pathways. The comprehensive introductory review in this book allows readers to overview state-of-the-art terahertz spectroscopic techniques. In addition, the skillful description of the experiments is highly informative for readers in ultrafast magnonics, ultrafast optics, terahertz technology and plasmonic science.

Download or read book Enhanced Polarisation Control and Extreme Electric Fields written by Connor Devyn William Mosley and published by Springer Nature. This book was released on 2021-03-25 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis reports advances in terahertz time-domain spectroscopy, relating to the development of new techniques and components that enhance the experimentalist’s control over the terahertz polarisation state produced by photoconductive emitters. It describes how utilising the dynamic magnetoelectric response at THz frequencies, in the form of electromagnons, can probe material properties at a transition between two magnetically ordered phases. Additionally, preliminary investigations into the properties of materials exposed to extreme terahertz optical electric fields are reported. The work presented in this thesis may have immediate impacts on the study of anisotropic media at THz frequencies, with photoconductive emitters and detectors being the most commonly used components for commercially available terahertz spectroscopy and imaging systems, and by providing a new way to study the nature of magnetic phase transitions in multiferroics. In the longer term the increased understanding of multiferroics yielded by ultrafast spectroscopic methods, including terahertz time-domain spectroscopy, may help develop new magnetoelectric and multiferroic materials for applications such as spintronics.

Download or read book Ultrafast Phenomena XVI written by Paul Corkum and published by Springer Science & Business Media. This book was released on 2010-03-23 with total page 1031 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrafast Phenomena XVI presents the latest advances in ultrafast science, including both ultrafast optical technology and the study of ultrafast phenomena. It covers picosecond, femtosecond and attosecond processes relevant to applications in physics, chemistry, biology, and engineering. Ultrafast technology has a profound impact in a wide range of applications, amongst them biomedical imaging, chemical dynamics, frequency standards, material processing, and ultrahigh speed communications. This book summarizes the results presented at the 16th International Conference on Ultrafast Phenomena and provides an up-to-date view of this important and rapidly advancing field.

Download or read book Spin Dynamics and Damping in Ferromagnetic Thin Films and Nanostructures written by Anjan Barman and published by Springer. This book was released on 2017-12-27 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive overview of the latest developments in the field of spin dynamics and magnetic damping. It discusses the various ways to tune damping, specifically, dynamic and static control in a ferromagnetic layer/heavy metal layer. In addition, it addresses all optical detection techniques for the investigation of modulation of damping, for example, the time-resolved magneto-optical Kerr effect technique.

Download or read book Ultra High Density Magnetic Recording written by Gaspare Varvaro and published by CRC Press. This book was released on 2016-03-30 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: Today magnetic recording is still the leading technology for mass data storage. Its dominant role is being reinforced by the success of cloud computing, which requires storing and managing huge amounts of data on a multitude of servers. Nonetheless, the hard-disk storage industry is presently at a crossroads as the current magnetic recording techno

Download or read book Spintronics Handbook Second Edition Spin Transport and Magnetism written by Evgeny Y. Tsymbal and published by CRC Press. This book was released on 2019-05-09 with total page 670 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spintronics Handbook, Second Edition offers an update on the single most comprehensive survey of the two intertwined fields of spintronics and magnetism, covering the diverse array of materials and structures, including silicon, organic semiconductors, carbon nanotubes, graphene, and engineered nanostructures. It focuses on seminal pioneering work, together with the latest in cutting-edge advances, notably extended discussion of two-dimensional materials beyond graphene, topological insulators, skyrmions, and molecular spintronics. The main sections cover physical phenomena, spin-dependent tunneling, control of spin and magnetism in semiconductors, and spin-based applications.

Download or read book Multidimensional Time Resolved Spectroscopy written by Tiago Buckup and published by Springer. This book was released on 2018-12-07 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Topics in Current Chemistry Collections presents critical reviews from the journal Topics in Current Chemistry organized in topical volumes. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field.

Download or read book Nonequilibrium Dynamics of Collective Excitations in Quantum Materials written by Edoardo Baldini and published by Springer. This book was released on 2018-03-28 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book studies the dynamics of fundamental collective excitations in quantum materials, focusing on the use of state-of-the-art ultrafast broadband optical spectroscopy. Collective behaviour in solids lies at the origin of several cooperative phenomena that can lead to profound transformations, instabilities and phase transitions. Revealing the dynamics of collective excitations is a topic of pivotal importance in contemporary condensed matter physics, as it provides information on the strength and spatial distribution of interactions and correlation. The experimental framework explored in this book relies on setting a material out-of-equilibrium by an ultrashort laser pulse and monitoring the photo-induced changes in its optical properties over a broad spectral region in the visible or deep-ultraviolet. Collective excitations (e.g. plasmons, excitons, phonons...) emerge either in the frequency domain as spectral features across the probed range, or in the time domain as coherent modes triggered by the pump pulse. Mapping the temporal evolution of these collective excitations provides access to the hierarchy of low-energy phenomena occurring in the solid during its path towards thermodynamic equilibrium. This methodology is used to investigate a number of strongly interacting and correlated materials with an increasing degree of internal complexity beyond conventional band theory.

Download or read book Spin Current written by Sadamichi Maekawa and published by Oxford University Press. This book was released on 2017 with total page 541 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a new branch of physics and technology, called spin-electronics or spintronics, the flow of electrical charge (usual current) as well as the flow of electron spin, the so-called "spin current", are manipulated and controlled together. This book is intended to provide an introduction and guide to the new physics and applications of spin current.

Download or read book Handbook of Magnetism and Magnetic Materials written by Michael Coey and published by Springer. This book was released on 2021-11-19 with total page 1679 pages. Available in PDF, EPUB and Kindle. Book excerpt: This handbook presents a comprehensive survey of magnetism and magnetic materials. The dramatic advances in information technology and electromagnetic engineering make it necessary to systematically review the approved key knowledge and summarize the state of the art in this vast field within one seminal reference work. The book thus delivers up-to-date and well-structured information on a wealth of topics encompassing all fundamental aspects of the underlying physics and materials science, as well as advanced experimental methodology and applications. It features coverage of the host of fascinating and complex phenomena that arise from the use of magnetic fields in e.g. chemistry and biology. Edited by two internationally renowned scholars and featuring authored chapters from leading experts in the field, Springer’s Handbook of Magnetism and Magnetic Materials is an invaluable source of essential reference information for a broad audience of students, researchers, and magnetism professionals.