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Magnetization Dynamics in Diluted Magnetic Semiconductor Heterostructures

Author : Martin Kneip

Publisher : GRIN Verlag

Page : 274 pages

File Size : 36,7 MB

Release : 2009-02-17

Category : Science

ISBN : 3640269454

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Book Description

Doctoral Thesis / Dissertation from the year 2008 in the subject Physics - Theoretical Physics, grade: sehr gut (1,0), University of Dortmund, language: English, abstract: In this thesis spin dynamics in (Zn,Mn)Se/(Zn,Be)Se and (Cd,Mn)Te/(Cd,Mg)Te DMS quantum well heterostructures with a type-I band alignment are studied, where the carriers are quantum confined. Especially the important role of free carriers in heating of the Mn-system, by its interaction with photoexcited carriers with excess kinetic energy, and in the cooling of the Mn-system in the presence of cold background carriers, provided by modulation doping, is established. The studies are separated in three chapters. In the fourth chapter of this thesis, new results on energy and spin transfer between free carriers and Mn-ion system are presented. Contributions of direct heating of the Mn-system by photocarriers and indirect heating via nonequilibrium phonons are distinguished and their competition is discussed. In the fifth chapter dynamics of spin-lattice relaxation of magnetic Mn-ions in DMS QW heterostructures is investigated and new experimental studies on (Zn,Mn)Se/(Zn,Be)Se heterostructures are shown. Crucial for spintronic devices is the ability to tune the spin relaxation time precisely, as the spin relaxation time is important in double respects. On the one hand spin polarization must be conserved over long times and distances, if the spin shall be processed or stored in a region, which is spatial separated from the spin-injector. Especially for the possibility of utilizing spins as quantum bits for quantum information processing, long spin polarization is needed. On the other hand short spin relaxation time is needed for fast switching between different spin-states. For instance semiconductor lasers can be switched off extremely fast by reorientation of spin. This very relevant topic is devoted the sixth chapter, before the thesis is summarized in the last chapter. Especially for one of the biggest drawbacks for precise tuning, that the magnetization dynamics in DMS cannot be controlled separately from the static magnetization, solutions via electric field control of the magnetization dynamics or via the technological concept of “digital alloying” are presented.precise tuning, that the magnetization dynamics in DMS cannot be controlled separately from the static magnetization, solutions via electric field control of the magnetization dynamics or via the technological concept of “digital alloying” are presented.



Introduction to the Physics of Diluted Magnetic Semiconductors

Author : Jan A. Gaj

Publisher : Springer Science & Business Media

Page : 484 pages

File Size : 23,76 MB

Release : 2011-01-12

Category : Science

ISBN : 3642158560

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Book Description

As materials whose semiconducting properties are influenced by magnetic ions, DMSs are central to the emerging field of spintronics. This volume focuses both on basic physical mechanisms (e.g. carrier-ion and ion-ion interactions), and resulting phenomena.



Ultrafast Magnetism I

Author : Jean-Yves Bigot

Publisher : Springer

Page : 361 pages

File Size : 13,40 MB

Release : 2014-08-05

Category : Science

ISBN : 3319077430

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Book Description

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.



Comprehensive Semiconductor Science and Technology

Author :

Publisher : Newnes

Page : 3572 pages

File Size : 19,29 MB

Release : 2011-01-28

Category : Science

ISBN : 0080932282

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Book Description

Semiconductors are at the heart of modern living. Almost everything we do, be it work, travel, communication, or entertainment, all depend on some feature of semiconductor technology. Comprehensive Semiconductor Science and Technology, Six Volume Set captures the breadth of this important field, and presents it in a single source to the large audience who study, make, and exploit semiconductors. Previous attempts at this achievement have been abbreviated, and have omitted important topics. Written and Edited by a truly international team of experts, this work delivers an objective yet cohesive global review of the semiconductor world. The work is divided into three sections. The first section is concerned with the fundamental physics of semiconductors, showing how the electronic features and the lattice dynamics change drastically when systems vary from bulk to a low-dimensional structure and further to a nanometer size. Throughout this section there is an emphasis on the full understanding of the underlying physics. The second section deals largely with the transformation of the conceptual framework of solid state physics into devices and systems which require the growth of extremely high purity, nearly defect-free bulk and epitaxial materials. The last section is devoted to exploitation of the knowledge described in the previous sections to highlight the spectrum of devices we see all around us. Provides a comprehensive global picture of the semiconductor world Each of the work's three sections presents a complete description of one aspect of the whole Written and Edited by a truly international team of experts



Optical Phenomena in Semiconductor Structures of Reduced Dimensions

Author : D.J. Lockwood

Publisher : Springer Science & Business Media

Page : 443 pages

File Size : 10,79 MB

Release : 2012-12-06

Category : Science

ISBN : 9401119120

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Book Description

Remarkable advances in semiconductor growth and processing technologies continue to have a profound impact on condensed-matter physics and to stimulate the invention of novel optoelectronic effects. Intensive research on the behaviors of free carriers has been carried out in the two-dimensional systems of semiconductor heterostructures and in the one and zero-dimensional systems of nanostructures created by the state-of-the-art fabrication methods. These studies have uncovered unexpected quantum mechanical correlations that arise because of the combined effects of strong electron-electron interactions and wave function confinement associated with reduced dimensionality. The investigations of these phenomena are currently at the frontiers of condensed-matter physics. They include areas like the fractional quantum Hall effect, the dynamics of electrons on an ultra short (femtosecond) time scale, electron behavior in quantum wires and dots, and studies of electron tunneling phenomena in ultra small semiconductor structures. Optical techniques have made important contributions to these fields in recent years, but there has been no coherent review of this work until now. The book provides an overview of these recent developments that will be of interest to semiconductor materials scientists in university, government and industrial laboratories.



Electric-Field Control of Magnetization and Electronic Transport in Ferromagnetic/Ferroelectric Heterostructures

Author : Sen Zhang

Publisher : Springer Science & Business Media

Page : 143 pages

File Size : 34,32 MB

Release : 2014-04-10

Category : Science

ISBN : 3642548393

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Book Description

This book mainly focuses on the investigation of the electric-field control of magnetism and spin-dependent transportation based on a Co40Fe40B20(CoFeB)/Pb(Mg1/3Nb2/3)0.7Ti0.3O3(PMN-PT) multiferroic heterostructure. Methods of characterization and analysis of the multiferroic properties with in situ electric fields are induced to detect the direct magnetoelectric (ME) coupling. A switchable and non-volatile electric field control of magnetization in CoFeB/PMN-PT(001) structures is observed at room temperature, and the mechanism of direct coupling between the ferroelectric domain and ferromagnetic film due to the combined action of 109° ferroelastic domain switching in PMN-PT and the absence of magnetocrystalline anisotropy in CoFeB is demonstrated. Moreover, the electric-field control of giant magnetoresistance is achieved in a CoFeB-based spin valve deposited on top of (011) oriented PMN-PT, which offers an avenue for implementing electric-writing and magnetic-reading random access memory at room temperature. Readers will learn the basic properties of multiferroic materials, many useful techniques related to characterizing multiferroics and the interesting ME effect in CoFeB/PMN-PT structures, which is significant for applications.



Dynamical Properties of Unconventional Magnetic Systems

Author : A.T. Skjeltorp

Publisher : Springer Science & Business Media

Page : 378 pages

File Size : 22,26 MB

Release : 2012-12-06

Category : Science

ISBN : 9401149887

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Book Description

Magnetism encompasses a wide range of systems and physical phenomena, and its study has posed and exposed both important fundamental problems and many practical applications. Recently, several entirely new phenomena have thus been discovered, generated through cooperative behaviour which could not have been predicted from a knowledge of `one-spin' states. At the same time, advances in sample preparation, experimental technique, apparatus and radiation sources, have led to increasing precision in the investigation and exposure of greater subtleties in magnetic thin films, multilayers and other systems. Examples of unexpected and conceptually new phenomena occur in strongly correlated and fluctuating quantum systems, producing effects such as Haldane and spin-Peierls gaps, solitons, quantum spin glasses and spin liquids. The discovery and elucidation of these `emerging properties' is a central theme in modern condensed matter physics. The present book comprises a series of chapters by world experts, covering both theoretical and experimental aspects. The approach is pedagogical and tutorial, but fully up to date, covering the latest research. The level is appropriate to graduate researchers who may either be just moving into the field or who are already active in condensed matter physics.



Research in Progress

Author :

Publisher :

Page : 302 pages

File Size : 15,30 MB

Release : 1992

Category : Military research

ISBN :

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Handbook of Spin Transport and Magnetism

Author : Evgeny Y. Tsymbal

Publisher : CRC Press

Page : 797 pages

File Size : 12,41 MB

Release : 2016-04-19

Category : Science

ISBN : 1439803781

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Book Description

In the past several decades, the research on spin transport and magnetism has led to remarkable scientific and technological breakthroughs, including Albert Fert and Peter Grunberg's Nobel Prize-winning discovery of giant magnetoresistance (GMR) in magnetic metallic multilayers. Handbook of Spin Transport and Magnetism provides a comprehensive, bal



Spin Physics in Semiconductors

Author : Mikhail I. Dyakonov

Publisher : Springer

Page : 546 pages

File Size : 40,42 MB

Release : 2017-10-04

Category : Technology & Engineering

ISBN : 3319654365

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Book Description

This book offers an extensive introduction to the extremely rich and intriguing field of spin-related phenomena in semiconductors. In this second edition, all chapters have been updated to include the latest experimental and theoretical research. Furthermore, it covers the entire field: bulk semiconductors, two-dimensional semiconductor structures, quantum dots, optical and electric effects, spin-related effects, electron-nuclei spin interactions, Spin Hall effect, spin torques, etc. Thanks to its self-contained style, the book is ideally suited for graduate students and researchers new to the field.