Ultrafast Dynamics of Electronic Structure and Domain Nucleation During Photo-induced Phase Transition in FeRh PDF Download

Author: Naman Agarwal
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: Junjie Li
Publisher:
ISBN:
Category : Physics
Languages : en
Pages :

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ABSTRACT: The thesis presents the recent development of the 3rd generation femtosecond electron diffractometer in Professor Jim Cao's group and its application to study ultrafast processes in real time. The research activities cover two main subjects: photoinduced structural phase transition (PIPT) in colossal magnetoresistive (CMR) materials and the dynamics of electron emission and the associated residual charge redistribution in targets during the early stage of laser ablation. In the study of PIPT in CMR materials, a direct and real time measurement of photoinduced structure phase transition in single crystal La0.84Sr0.16MnO3 and LaMnO3 was performed by using femtosecond electron diffraction. The melting of orthorhombic lattice ordering under femtosecond optical excitation is found involving two distinct processes with different time scales, an initial fast melting of orthorhombic phase in 3 ps and a subsequent much slower transformation in 50 ps and longer timescales. The fast process can be attributed to the initial melting of orthorhombic phase induced by the Mn-O bond change that is driven by the quenching of the Jahn-Teller distortion following the photo-excitation. The slow process is associated with the growing of newly formed structure domain from excited sites to the neighboring non-excited orthorhombic sites. In the second project, two new techniques, namely femtosecond electron shadow imaging and ultrafast electron deflectometry, were developed. These two complementary techniques provide both a global view and local prospect of the associated transient electric field and charge expansion dynamics. The results reveal that the charge cloud above the target surface is predominantly composed of thermally ejected electrons and the charge cloud expands with a fast front-layer speed exceeding 107 m/s. The average electric field strength of the charge cloud induced by a pump fluence of 2.2 J/cm2 is estimated to be on the order of ~2.4x105 V/m. For the temporal evolution of residual charges on the target, the results show that residual charges in metals can redistribute themselves almost instantly, abiding by the boundary conditions and Maxwell equations in the same way as they would at electrostatic equilibrium condition. However, residual charges in dielectrics are confined within the excited area for hundreds of picoseconds and beyond. These observations provide an experimental support to the alleged coulomb explosion phenomenon in previous studies, as well as a reference for modeling residual charge dynamics. In addition, a 1-D molecular dynamics simulation of coherent lattice motion in laser excited thin film is presented in the last section of this thesis. Using this simulation, both the displacement and expansion at each lattice site along the 1-D atomic chain can be traced as a function of delay time. In particular, the simulation shows that the electronic thermal stress is responsible for driving the lattice motion at the early stage, which matches very well with our FED experimental data obtained in the study of ultrafast heating of free-standing metal films.

Author: J. Hastings
Publisher: IOS Press
ISBN: 1643681338
Category : Science
Languages : en
Pages : 272

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Many X-Ray Free-Electron Lasers (X-FELs) have been designed, built and commissioned since the first lasing of the Linac Coherent Light Source in the hard and soft X-ray regions, and great progress has been made in improving their performance and extending their capabilities. Meanwhile, experimental techniques to exploit the unique properties of X-FELs to explore atomic and molecular systems of interest to physics, chemistry, biology and the material sciences have also been developed. As a result, our knowledge of atomic and molecular science has been greatly extended. Nevertheless, there is still much to be accomplished, and the potential for discovery with X-FELs is still largely unexplored. The next generation of scientists will need to be well versed in both particle beams/FEL physics and X-ray photon science. This book presents material from the Enrico Fermi summer school: Physics of and Science with X-Ray Free-Electron Lasers, held at the Enrico Fermi International School of Physics in Varenna, Italy, from 26 June - 1 July 2017. The lectures presented at the school were aimed at introducing graduate students and young scientists to this fast growing and exciting scientific area, and subjects covered include basic accelerator and FEL physics, as well as an introduction to the main research topics in X-FEL-based biology, atomic molecular optical science, material sciences, high-energy density physics and chemistry. Bridging the gap between accelerator/FEL physicists and scientists from other disciplines, the book will be of interest to all those working in the field.

Author: J.-J. Yeh
Publisher: Gordon & Breach Science Pub
ISBN: 9782881245855
Category : Science
Languages : en
Pages : 223

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This book presents the results of atomic calculations of subshell and total photoionization cross-sections and asymmetry parameters as a function of photon energies below 1.5 KeV. The book provides graphical data for the dipole-length approximation and includes ASCII text data on floppy diskettes for all approximations calculated in the same model. The data files may be exported to IBM PC/XT and AT or compatible computers or printers. Installation requires 6Mb of temporary memory. j.J. Yeh, AT&T Bell Laboratories, Murray Hill, New Jersey, USA

Author: Simon Woodford
Publisher: Forschungszentrum Jülich
ISBN: 3893365362
Category : Magnetic fields
Languages : en
Pages : 137

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Author: Wayne M. Saslow
Publisher: Elsevier
ISBN: 008050521X
Category : Science
Languages : en
Pages : 809

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A very comprehensive introduction to electricity, magnetism and optics ranging from the interesting and useful history of the science, to connections with current real-world phenomena in science, engineering and biology, to common sense advice and insight on the intuitive understanding of electrical and magnetic phenomena. This is a fun book to read, heavy on relevance, with practical examples, such as sections on motors and generators, as well as `take-home experiments' to bring home the key concepts. Slightly more advanced than standard freshman texts for calculus-based engineering physics courses with the mathematics worked out clearly and concisely. Helpful diagrams accompany the discussion. The emphasis is on intuitive physics, graphical visualization, and mathematical implementation. - Electricity, Magnetism, and Light is an engaging introductory treatment of electromagnetism and optics for second semester physics and engineering majors. - Focuses on conceptual understanding, with an emphasis on relevance and historical development. - Mathematics is specific and avoids unnecessary technical development. - Emphasis on physical concepts, analyzing the electromagnetic aspects of many everyday phenomena, and guiding readers carefully through mathematical derivations. - Provides a wealth of interesting information, from the history of the science of electricity and magnetism, to connections with real world phenomena in science, engineering, and biology, to common sense advice and insight on the intuitive understanding of electrical and magnetic phenomena

Author: Charles W. Carter
Publisher: Gulf Professional Publishing
ISBN: 9780121827779
Category : Computer simulation
Languages : en
Pages : 756

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Annotation Accurate molecular structures is vital for rational drug design and for structure based functional studies directed toward the development of effective therapeutic agents and drugs. Crystallography can reliably predict structure, both in terms of folding and atomic details of bonding. * Phases * Map interpretation and refinement * Analysis and software.

Author: James F. Scott
Publisher: Springer Science & Business Media
ISBN: 3662043076
Category : Technology & Engineering
Languages : en
Pages : 255

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This is the first comprehensive book on ferroelectric memories which contains chapters on device design, processing, testing, and device physics, as well as on breakdown, leakage currents, switching mechanisms, and fatigue. State-of-the-art device designs are included and illustrated among the books many figures. More than 500 up-to-date references and 76 problems make it useful as a research reference for physicists, engineers and students.

Author: Surender Kumar Sharma
Publisher: Springer
ISBN: 3319929550
Category : Technology & Engineering
Languages : en
Pages : 612

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This book focuses on the widely used experimental techniques available for the structural, morphological, and spectroscopic characterization of materials. Recent developments in a wide range of experimental techniques and their application to the quantification of materials properties are an essential side of this book. Moreover, it provides concise but thorough coverage of the practical and theoretical aspects of the analytical techniques used to characterize a wide variety of functional nanomaterials. The book provides an overview of widely used characterization techniques for a broad audience: from beginners and graduate students, to advanced specialists in both academia and industry.

Author: Joseph Woicik
Publisher: Springer
ISBN: 3319240439
Category : Science
Languages : en
Pages : 576

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This book provides the first complete and up-to-date summary of the state of the art in HAXPES and motivates readers to harness its powerful capabilities in their own research. The chapters are written by experts. They include historical work, modern instrumentation, theory and applications. This book spans from physics to chemistry and materials science and engineering. In consideration of the rapid development of the technique, several chapters include highlights illustrating future opportunities as well.