Structural Modifications Of Epitaxial Mgo Based Tunnel Barriers For Engineering Magneto Transport Properties Of Magnetic Tunnel Junction Devices
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Structural Modifications Of Epitaxial Mgo Based Tunnel Barriers For Engineering Magneto Transport Properties Of Magnetic Tunnel Junction Devices
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Author : Eran Amsellem
language : en
Publisher:
Release Date : 2015
Structural Modifications Of Epitaxial Mgo Based Tunnel Barriers For Engineering Magneto Transport Properties Of Magnetic Tunnel Junction Devices written by Eran Amsellem and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Magnesium Boron Oxide Tunnel Barriers
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Author : John Creighton Read
language : en
Publisher:
Release Date : 2009
Magnesium Boron Oxide Tunnel Barriers written by John Creighton Read and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
In this dissertation I investigate the materials physics of thin film growth processes for magnetic tunnel junctions (MTJs) and Josephson junctions (JJs). The studies I present focus primarily on the chemical, electronic, and structural properties of the tunnel barriers and their interfaces with the adjacent electrodes. I developed a growth process for making MgO (MgBO)-based MTJs, studied this film stack in detail, and also examined the materials properties of MgB2 oxidation processes and AlN tunnel barrier formation for JJ development. I conducted x-ray photoelectron spectroscopy (XPS) studies on CoFeB / MgO bilayers to explore the MgO growth process. MgO that is rf sputtered directly on CoFeB or on a thin Mg protective layer forms MgBO with promising physical and chemical properties. Post-growth annealing reduces Fe and Co oxides formed in the deposition process through a reaction of B from the electrode with O in the transition metal oxides. Annealing also causes an atomic rearrangement of the Mg, B, and O species in these barriers. In sputtered MTJs with thin barriers, reaction between B from the electrode and sputter deposited MgO is an inherent part of the formation of MgO-based MTJs. I studied the correlated results of scanning tunneling electron microscopy (STEM) utilizing electron energy-loss spectroscopy (EELS), scanning tunneling spectroscopy (STS), current-in-plane tunneling (CIPT), and magnetometry studies. These investigations show that MgBO barriers have fewer low energy defect states than MgO barriers and comparison of MTJs with MgBO barriers with MTJs with Mg/MgO bilayer barriers shows that MgBO barriers yield higher TMR values and lower RA values than MgO barriers of comparable thickness. MgBO MTJs are also compatible with permalloy-B (PyB) free electrodes that show desirable magnetic characteristics. The electrode B content is important for the formation of low defect MgBO barriers and for the use of superior Py-based electrode materials for spin torque magnetic random access memory (MRAM) and magnetic sensor applications. I also studied MgBO barriers in an exploration of the oxidation of MgB2 thin films. The oxidation of the MgB2 film surface forms MgBO that is chemically similar to the MgBO materials formed in MTJ structures. Exposure to N2 or O2 promotes formation of MgO on the MgB2 film surface which becomes completely composed of MgO if the oxidation process is carried out at elevated temperatures for an extended time. Lower temperatures form oxides similar to the native surface oxide, and promote formation of elemental B, and B sub-oxide near the film surface. These B species are likely to effect JJs made with these barrier formation processes. These chemical studies provide insights into optimal MgBO barrier formation techniques for future MgB2 -based JJ devices. Finally, I started developing growth processes for AlN tunnel barriers formed both by N beam exposure of Al films and by reactive rf sputtering of AlN in either Ar or N2 for use in Nb / AlN / Nb JJs. Both AlN growth processes introduce O into the AlN film, which could possibly be controlled with the use of a getter material during barrier deposition. These XPS studies show that when a pure N2 atmosphere is used for reactive rf sputtering of AlN, the film growth nitridizes the underlying Nb film, similar to the way MgO oxidizes CoFeB. These studies provide some insights as to optimal AlN barrier formation for JJ structures that can now be further developed.
Handbook Of Spintronics
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Author : Yongbing Xu
language : en
Publisher: Springer
Release Date : 2015-10-14
Handbook Of Spintronics written by Yongbing Xu and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-10-14 with Science categories.
Over two volumes and 1500 pages, the Handbook of Spintronics will cover all aspects of spintronics science and technology, including fundamental physics, materials properties and processing, established and emerging device technology and applications. Comprising 60 chapters from a large international team of leading researchers across academia and industry, the Handbook provides readers with an up-to-date and comprehensive review of this dynamic field of research. The opening chapters focus on the fundamental physical principles of spintronics in metals and semiconductors, including an introduction to spin quantum computing. Materials systems are then considered, with sections on metallic thin films and multilayers, magnetic tunnelling structures, hybrids, magnetic semiconductors and molecular spintronic materials. A separate section reviews the various characterisation methods appropriate to spintronics materials, including STM, spin-polarised photoemission, x-ray diffraction techniques and spin-polarised SEM. The third part of the Handbook contains chapters on the state of the art in device technology and applications, including spin valves, GMR and MTJ devices, MRAM technology, spin transistors and spin logic devices, spin torque devices, spin pumping and spin dynamics and other topics such as spin caloritronics. Each chapter considers the challenges faced by researchers in that area and contains some indications of the direction that future work in the field is likely to take. This reference work will be an essential and long-standing resource for the spintronics community.
Tunnel Magnetoresistance In Epitaxially Grown Magnetic Tunnel Junctions Using Heusler Alloy Electrode And Mgo Barrier
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Author :
language : en
Publisher:
Release Date : 2009
Tunnel Magnetoresistance In Epitaxially Grown Magnetic Tunnel Junctions Using Heusler Alloy Electrode And Mgo Barrier written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
Epitaxially grown magnetic tunnel junctions (MTJs) with a stacking structure of Co2MnSi/MgO/CoFe were fabricated. Their tunnel magnetoresistance (TMR) effects were investigated. The TMR ratio and tunnelling conductance characteristics of MTJs were considerably different between those with an MgO barrier prepared using sputtering (SP-MTJ) and those prepared using EB evaporation (EB-MTJ). The EB-MTJ exhibited a very large TMR ratio of 217% at room temperature and 753% at 2 K. The bias voltage dependence of the tunnelling conductance in the parallel magnetic configuration for the EB-MTJ suggests that the observed large TMR ratio at RT results from the coherent tunnelling process through the crystalline MgO barrier. The tunnelling conductance in the anti-parallel magnetic configuration suggests that the large temperature dependence of the TMR ratio results from the inelastic spin-flip tunnelling process.
Process Development For Integration Of Cofeb Mgo Based Magnetic Tunnel Junction Mtj Device On Silicon
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Author : Shrinivas Pandharpure
language : en
Publisher:
Release Date : 2007
Process Development For Integration Of Cofeb Mgo Based Magnetic Tunnel Junction Mtj Device On Silicon written by Shrinivas Pandharpure and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Integrated circuits categories.
"Methods of communication and dissemination of information have changed dramatically with the emergence of the Internet and mobile phones. To sustain this revolution, we need reliable mass storage devices which would store information not only in large amount in small space but also for long time. Therefore, realizing high performance memory technologies is very critical for this revolution. This work contributes towards the development of one such technology; Magnetic Random Access Memory (MRAM) based on Magnetic Tunnel Junction (MTJ). The research conducted in this study is primarily focused on the process development for integrating MTJ on silicon. The film stack explored in this work is CoFeB/MgO-based. The relevant issues in this integration such as smooth bottom electrode preparation, low thermal budget, process chemistry and parameters, and MTJ patterning involving ion-milling have been addressed in this work. Ta and NiCr are evaluated as candidates for bottom electrode. Spin-on Glass (SOG)-based low temperature Inter Level Dielectric (ILD) process is developed. MTJ devices with varying sizes with four terminal contacts for on wafer testing have been designed and fabricated using the process developed. The devices exhibited Resistance-Area (RA) product in the range of 1-5 k[omega]micron2. Recent literature on MgO-based MTJ devices has reported values in a range of 0.1-1000 k[omega]micron2. . This data confirms the electrical integrity of the MTJ fabricated. The RA values have been observed to be unchanged on application of magnetic field (+-300Oe). Detailed investigations have been carried out to find possible causes for the absence of magnetic response from these junctions. These include XRD analysis of the MTJ stack for CoFeB crystallization and STEM-PEELS studies to investigate the chemical composition. 'Néel coupling' or 'Orange peel coupling' due to interface roughness is thought to be one of the main possible causes for magnetically inactive junctions. Suggestions for future are given on the basis of the results from the process and the experiments. In summary, a process has been developed for fabricating MTJ on silicon yielding desired values for junction resistivity. The magnetic response is extremely sensitive to film roughness at nanoscales and will require control of roughness at each step starting with wafer specification. It is concluded that with a control of surface roughness and recommended modifications in MTJ films, a CMOS compatible process for fabricating MTJ is plausible at RIT."--Abstract.
Fabrication Of Magnetic Tunnel Junctions With Epitaxial And Textured Ferromagnetic Layers
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Author :
language : en
Publisher:
Release Date : 2008
Fabrication Of Magnetic Tunnel Junctions With Epitaxial And Textured Ferromagnetic Layers written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.
This invention relates to magnetic tunnel junctions and methods for making the magnetic tunnel junctions. The magnetic tunnel junctions include a tunnel barrier oxide layer sandwiched between two ferromagnetic layers both of which are epitaxial or textured with respect to the underlying substrate upon which the magnetic tunnel junctions are grown. The magnetic tunnel junctions provide improved magnetic properties, sharper interfaces and few defects.
Spin Torque Effects In Mgo Based Magnetic Tunnel Junctions
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Author : Hsin-wei Tseng
language : en
Publisher:
Release Date : 2013
Spin Torque Effects In Mgo Based Magnetic Tunnel Junctions written by Hsin-wei Tseng and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
This thesis work focuses on understanding the fundamentals of the spintorque effect in MgO-based high tunneling magnetoresistance (TMR) magnetic tunnel junction (MTJ) nanopillar geometry devices. In order to achieve this goal, I have successfully established a reliable and repeatable high TMR and low resistance-area (RA) product MgO sputtering process at Cornell. Currently, we are capable of sputtering TMR (>100% with RA
Magnetism And Accelerator Based Light Sources
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Author : Hervé Bulou
language : en
Publisher: Springer Nature
Release Date : 2021-02-17
Magnetism And Accelerator Based Light Sources written by Hervé Bulou and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-02-17 with Science categories.
This open access book collects the contributions of the seventh school on Magnetism and Synchrotron Radiation held in Mittelwihr, France, from 7 to 12 October 2018. It starts with an introduction to the physics of modern X-ray sources followed by a general overview of magnetism. Next, light / matter interaction in the X-ray range is covered with emphasis on different types of angular dependence of X-ray absorption spectroscopy and scattering. In the end, two domains where synchrotron radiation-based techniques led to new insights in condensed matter physics, namely spintronics and superconductivity, are discussed. The book is intended for advanced students and researchers to get acquaintance with the basic knowledge of X-ray light sources and to step into synchrotron-based techniques for magnetic studies in condensed matter physics or chemistry.
Nanomagnetism And Spintronics
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Author : Teruya Shinjo
language : en
Publisher: Elsevier
Release Date : 2013-10-07
Nanomagnetism And Spintronics written by Teruya Shinjo and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-10-07 with Science categories.
The concise and accessible chapters of Nanomagnetism and Spintronics, Second Edition, cover the most recent research in areas of spin-current generation, spin-calorimetric effect, voltage effects on magnetic properties, spin-injection phenomena, giant magnetoresistance (GMR), and tunnel magnetoresistance (TMR). Spintronics is a cutting-edge area in the field of magnetism that studies the interplay of magnetism and transport phenomena, demonstrating how electrons not only have charge but also spin. This second edition provides the background to understand this novel physical phenomenon and focuses on the most recent developments and research relating to spintronics. This exciting new edition is an essential resource for graduate students, researchers, and professionals in industry who want to understand the concepts of spintronics, and keep up with recent research, all in one volume. Provides a concise, thorough evaluation of current research Surveys the important findings up to 2012 Examines the future of devices and the importance of spin current
Spin Current
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Author : Sadamichi Maekawa
language : en
Publisher: Oxford University Press
Release Date : 2017
Spin Current written by Sadamichi Maekawa and has been published by Oxford University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Science categories.
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.