Two-Dimensional Arrays of Vertically Packed Spin-Valves With
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Noninvasive Muscle Activity Imaging Using Magnetography
Noninvasive muscle activity imaging using magnetography Rodolfo R. Llinása,1,2, Mikhail Ustininb,2, Stanislav Rykunovb,2, Kerry D. Waltona,2, Guilherme M. Rabelloa,2, John Garciaa,2, Anna Boykob,2, and Vyacheslav Sychevb,2 aDepartment of Neuroscience and Physiology, Center for Neuromagnetism, New York University School of Medicine, New York, New York, 10016; and bKeldysh Institute of Applied Mathematics, Russian Academy of Sciences, Moscow, 125047 Russia Contributed by Rodolfo R. Llinás, November 19, 2019 (sent for review August 12, 2019; reviewed by Edgar Garcia-Rill and David Poeppel) A spectroscopic paradigm has been developed that allows the mag- Results netic field emissions generated by the electrical activity in the hu- The results obtained in the present set of functional tomo- man body to be imaged in real time. The growing significance of grams correspond to actual anatomical data, very much to imaging modalities in biology is evident by the almost exponential those obtained by head MRI, or by direct observation in other increase of their use in research, from the molecular to the ecolog- cases. Recordings were made from the head (Fig. 1), heart ical level. The method of analysis described here allows totally non- (Figs. 2 and 3), and several muscle groups (Figs. 4 and 5) at invasive imaging of muscular activity (heart, somatic musculature). rest and during voluntary contraction, or under conditions Such imaging can be obtained without additional methodological where muscles were intrinsically activated during muscle pain steps such as the use of contrast media. (Fig. 5). magnetoencephalography | magnetocardiography | magnetomyograph | Recordings with the Head in the Sensor Helmet. -
Arxiv:2008.00082V3 [Physics.Atom-Ph] 12 Oct 2020
Sensitive magnetometry in challenging environments Kai-Mei C. Fu,1 Geoffrey Z. Iwata,2, 3 Arne Wickenbrock,2, 3 and Dmitry Budker2, 3, 4 1University of Washington, Physics Department and Electrical and Computer Engineering Department, Seattle, WA, 98105, USA 2Helmholtz-Institut, GSI Helmholtzzentrum f¨ur Schwerionenforschung, 55128 Mainz, Germany 3Johannes Gutenberg-Universit¨atMainz, 55128 Mainz, Germany 4Department of Physics, University of California, Berkeley, CA 94720-7300, USA (Dated: October 13, 2020) State-of-the-art magnetic field measurements performed in shielded environments with carefully controlled conditions rarely reflect the realities of those applications envisioned in the introductions of peer-reviewed publications. Nevertheless, significant advances in magnetometer sensitivity have been accompanied by serious attempts to bring these magnetometers into the challenging working environments in which they are often required. This review discusses the ways in which various (predominantly optically-pumped) magnetometer technologies have been adapted for use in a wide range of noisy and physically demanding environments. I. INTRODUCTION of the sensor with the environment itself - it would be a difficult task indeed to convince a doctor to place a hot rubidium or cesium vapor cell inside a patient's body, no Magnetic fields are routinely measured with high sen- matter how well protected. sitivity to probe the physical processes that underlie a Unsurprisingly, utilization of enhanced measurement vast array of natural phenomena. From geological move- techniques and noise mitigation is an integral part of ments, solar flares, and atmospheric discharge, to inter- magnetometer development across many applications, cellular processes, neuronal communication in the brain, and is well documented across the literature. -
A Model of the Magnetic Fields Created by Single Motor Unit Compound Action Potentials in Skeletal Muscle Kevin Kit Parker and John P
948 IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, VOL. 44, NO. 10, OCTOBER 1997 A Model of the Magnetic Fields Created by Single Motor Unit Compound Action Potentials in Skeletal Muscle Kevin Kit Parker and John P. Wikswo, Jr.,* Member, IEEE Abstract—We have developed a computationally simple model Of particular interest is the MMG, although much of what for calculating the magnetic-field strength at a point due to a we state about the MMG is applicable to the MNG in the single motor unit compound action potential (SMUCAP). The appropriate context. The EMG and the MMG have similarities, motor unit is defined only in terms of its anatomical features, and the SMUCAP is approximated using the tripole model. The as they are both measurements of the same phenomena of distributed current density J is calculated within the volume propagation of action signals along an excitable fiber, that defined by the motor unit. The law of Biot and Savart can then are documented in the literature [1], [2]. Recordings made be cast in a form necessitating that J be integrated only over in our laboratory on single motor units (SMU’s) of the extens the region containing current sources or conductivity boundaries. or digitorum longus in rats [1] and a subsequent analysis of The magnetic-field strength is defined as the summation of the contributions to the field made by every muscle fiber in the motor the magnetic recording technique [3] showed two important unit. Applying this model to SMUCAP measurements obtained features of the MMG: the AF was less sensitive to the position using a high-resolution SUper Conducting Quantum Interference of the magnetometer than the electric potential recording Device (SQUID) magnetometer may yield information regarding was to electrode placement, and the AF associated with AC the distribution of action currents (AC’s) and the anatomical properties of single motor units within a muscle bundle. -
A Brief Review of Ferroelectric Control of Magnetoresistance in Organic Spin Valves Xiaoshan Xu University of Nebraska-Lincoln, [email protected]
University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Xiaoshan Xu Papers Research Papers in Physics and Astronomy 2018 A brief review of ferroelectric control of magnetoresistance in organic spin valves Xiaoshan Xu University of Nebraska-Lincoln, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/physicsxu Part of the Atomic, Molecular and Optical Physics Commons, Condensed Matter Physics Commons, and the Engineering Physics Commons Xu, Xiaoshan, "A brief review of ferroelectric control of magnetoresistance in organic spin valves" (2018). Xiaoshan Xu Papers. 11. https://digitalcommons.unl.edu/physicsxu/11 This Article is brought to you for free and open access by the Research Papers in Physics and Astronomy at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Xiaoshan Xu Papers by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. J Materiomics 4 (2018) 1e12 Contents lists available at ScienceDirect J Materiomics journal homepage: www.journals.elsevier.com/journal-of-materiomics/ A brief review of ferroelectric control of magnetoresistance in organic spin valves Xiaoshan Xu Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE 68588, USA article info abstract Article history: Magnetoelectric coupling has been a trending research topic in both organic and inorganic materials and Received 16 September 2017 hybrids. The concept of controlling magnetism using an electric field is particularly appealing in energy Received in revised form efficient applications. In this spirit, ferroelectricity has been introduced to organic spin valves to 8 November 2017 manipulate the magneto transport, where the spin transport through the ferromagnet/organic spacer Accepted 11 November 2017 interfaces (spinterface) are under intensive study. -
Optimisation of a Diamond Nitrogen Vacancy Centre Magnetometer for Sensing of Biological Signals
Optimisation of a diamond nitrogen vacancy centre magnetometer for sensing of biological signals August 26, 2020 []James L. Webb 1,∗, Luca Troise 1, Nikolaj W. Hansen 2, Jocelyn Achard 3, Ovidiu Brinza 3, Robert Staacke 4, Michael Kieschnick 4, Jan Meijer 4, Jean-Fran¸cois Perrier 2, Kirstine Berg Sørensen 1, Alexander Huck 1 and Ulrik Lund Andersen 1 Abstract 1 Sensing of signals from biological processes, such as action potential propagation in nerves, are essential for clinical diagnosis and basic understanding of physiology. Sensing can be performed electrically by placing sensor probes near or inside a liv- ing specimen or dissected tissue using well established electrophysiology techniques. However, these electrical probe techniques have poor spatial resolution and can- not easily access tissue deep within a living subject, in particular within the brain. An alternative approach is to detect the magnetic field induced by the passage of the electrical signal, giving the equivalent readout without direct electrical contact. Such measurements are performed today using bulky and expensive superconduct- ing sensors with poor spatial resolution. An alternative is to use nitrogen vacancy (NV) centres in diamond that promise biocompatibilty and high sensitivity without arXiv:2004.02279v2 [quant-ph] 24 Aug 2020 cryogenic cooling. In this work we present advances in biomagnetometry using NV centres, demonstrating magnetic field sensitivity of approximately 100 pT/√Hz in the DC/low frequency range using a setup designed for biological measurements. Biocompatibility of the setup with a living sample (mouse brain slice) is studied and optimized, and we show work toward sensitivity improvements using a pulsed magnetometry scheme. -
Spin Polarized Current Phenomena in Magnetic Tunnel Junctions
SPIN POLARIZED CURRENT PHENOMENA IN MAGNETIC TUNNEL JUNCTIONS A DISSERTATION SUBMITTED TO THE DEPARTMENT OF APPLIED PHYSICS AND THE COMMITTEE ON GRADUATE STUDIES OF STANFORD UNIVERSITY IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Li Gao September 2009 © Copyright by Li Gao 2009 All Rights Reserved ii I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. _________________________________________________ (James S. Harris) Principal Advisor I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. _________________________________________________ (Stuart S. P. Parkin) co-Principal Advisor I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. _________________________________________________ (Walter A. Harrison) Approved for the University Committee On Graduate Studies. _________________________________________________ iii iv Abstract Spin polarized current is of significant importance both scientifically and technologically. Recent advances in film growth and device fabrication in spintronics make possible an entirely new class of spin-based devices. An indispensable element in all these devices is the magnetic tunnel junction (MTJ) which has two ferromagnetic electrodes separated by an insulator barrier of atomic scale. When electrons flow through a MTJ, they become spin-polarized by the first magnetic electrode. Thereafter, the interplay between the spin polarized current and the second magnetic layer manifests itself via two phenomena: i.) Tunneling magnetoresistance (TMR) effect. -
Spin-Valve Effect in Nife/Mos2/Nife Junctions
Spin-valve Effect in NiFe/MoS2/NiFe Junctions Weiyi Wang1,2, Awadhesh Narayan3,4, Lei Tang1, Kapildeb Dolui5, Yanwen Liu1,2, Xiang Yuan1,2, Yibo Jin1, Yizheng Wu1,2, Ivan Rungger3, Stefano Sanvito3, Faxian Xiu1,2, 1State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China 2Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China 3School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland 4Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. 5Graphene Research Center and Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore Correspondence and requests for materials should be addressed to F.X. (E-mail: [email protected]) 1 Abstract Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have been recently proposed as appealing candidate materials for spintronic applications owing to their distinctive atomic crystal structure and exotic physical properties arising from the large bonding anisotropy. Here we introduce the first MoS2-based spin-valves that employ monolayer MoS2 as the nonmagnetic spacer. In contrast with what expected from the semiconducting band-structure of MoS2, the vertically sandwiched-MoS2 layers exhibit metallic behavior. This originates from their strong hybridization with the Ni and Fe atoms of the Permalloy (Py) electrode. The spin-valve effect is observed up to 240 K, with the highest magnetoresistance (MR) up to 0.73% at low temperatures. The experimental work is accompanied by the first principle electron transport calculations, which reveal an MR of ~ 9% for an ideal Py/MoS2/Py junction. -
Pseudo Spin Valve Behavior in Colloidally Prepared Nanoparticle Films Benjamin H
Letter Cite This: ACS Appl. Electron. Mater. 2019, 1, 1065−1069 pubs.acs.org/acsaelm Pseudo Spin Valve Behavior in Colloidally Prepared Nanoparticle Films Benjamin H. Zhou† and Jeffrey D. Rinehart*,†,‡ † ‡ Materials Science and Engineering Program and Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States *S Supporting Information ABSTRACT: Magnetoresistance provides a high-precision, versatile sensing mechanism that has continuously advanced in tandem with methods for top-down engineering of high-precision multilayer devices. Materials composed of solution-prepared nanocrystals can replicate some of the behavior of traditional magnetoresistive stacks but are limited by their intrinsic response mechanism: a gradual shift from low to high resistance with field. To fundamentally alter this behavior, we demonstrate the first instance of any form of spin valve behavior arising from a nanoparticle composite magnetoresistor. Single-layer films of varying CoFe2O4 to Fe3O4 nanoparticle ratios are used to show how the low-field sensitivity can be tuned to values exceeding those of either single-component material. Additionally, the sensitivity is shown to be a simple function of the magnetization of the individual component materials. KEYWORDS: colloidal nanomaterials, composite materials, spintronics, magnetoresistance, magnetism oon after the revolutionary discovery of giant magneto- Conversely, in a granular or nanocomposite magnetoresistor, S resistance (GMR) in multilayered structures,1,2 an application of an external magnetic field results in individual analogous effect was observed for magnetic grains in particle moments deviating from their original alignment with 3−7 Δ − conducting or insulating matrices. In this formulation, the the local anisotropy axes (maximum R/Rmax; Figure 1a ii,iv) matrix material acts as the spin-selecting junction between toward parallel alignment with the external field axis magnetically oriented grains, and the lack of structural (minimum ΔR/R; Figure1a−i,iii). -
Muscle Fatigue Revisited - Insights from Optically Pumped Magnetometers
bioRxiv preprint doi: https://doi.org/10.1101/2021.05.03.442396; this version posted May 4, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Muscle fatigue revisited - Insights from optically pumped magnetometers Davide Sometti2,3,6, Lorenzo Semeia5,6, Hui Chen2,3, Juergen Dax2,3, Cornelius Kronlage1, Sangyeob Baek2,3,11, Milena Kirchgässner1, Alyssa Romano1, Johanna Heilos1, Deborah Staber1, Julia Oppold1, Giulia Righetti2,3,4, Thomas Middelmann5, Christoph Braun2,3,6,7, Philip Broser8, Justus Marquetand 1,2,3 1 Department of Epileptology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany 2 Department of Neural Dynamics and Magnetoencephalography, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany 3 MEG-Center, University of Tübingen, Tübingen, Germany 4 Center for Ophthalmology, University of Tübingen, Tübingen, Germany 5 IDM/fMEG Center of the Helmholtz Center Munich at the University of Tübingen, University of Tübingen, German Center for Diabetes Research (DZD), Tübingen, Germany 6 Graduate Training Centre of Neuroscience, International Max Planck Research School, University of Tübingen, 72074 Tübingen, Germany 7 Department of Biosignals, Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany 8 CIMeC, Center for Mind/Brain Sciences, University of Trento, Rovereto, Italy 9 DiPsCo, Department of Psychology and Cognitive Science, University of Trento, Rovereto, Italy 10 Children's Hospital of Eastern Switzerland, Sankt Gallen, Switzerland. 11 University of Freiburg, Freiburg, Germany Corresponding Author: Justus Marquetand Email: [email protected] Hoppe-Seyler-Str.3 72076 Tübingen Germany bioRxiv preprint doi: https://doi.org/10.1101/2021.05.03.442396; this version posted May 4, 2021. -
Miniaturized Magnetic Sensors for Implantable Magnetomyography
PROGRESS REPORT www.advmattechnol.de Miniaturized Magnetic Sensors for Implantable Magnetomyography Siming Zuo, Hadi Heidari,* Dario Farina, and Kianoush Nazarpour* 1972.[1] Cohen and Gilver defined the mag- Magnetism-based systems are widely utilized for sensing and imaging netomyogram signal to be a recording of biological phenomena, for example, the activity of the brain and the heart. one component of the magnetic field vector versus time, where the magnetic field at Magnetomyography (MMG) is the study of muscle function through the inquiry the point of measurement is due to cur- of the magnetic signal that a muscle generates when contracted. Within the rents generated by skeletal muscle. The last few decades, extensive effort has been invested to identify, characterize correspondence between the MMG method and quantify the magnetomyogram signals. However, it is still far from a and its electrical counterpart, that is the miniaturized, sensitive, inexpensive and low-power MMG sensor. Herein, the electromyography (EMG) technique.[2] Both state-of-the-art magnetic sensing technologies that have the potential to realize stems directly from the Maxwell–Ampère law, as illustrated in Figure 1a. However, a low-profile implantable MMG sensor are described. The technical challenges the ease at which the EMG signal can be associated with the detection of the MMG signals, including the magnetic field recorded and the similarity between the of the Earth and movement artifacts are also discussed. Then, the development temporal and spectral characteristics of the of efficient magnetic technologies, which enable sensing pico-Tesla signals, MMG and EMG signals have encouraged is advocated to revitalize the MMG technique. -
Noninvasive Muscle Activity Imaging Using Magnetography
Noninvasive muscle activity imaging using magnetography Rodolfo R. Llinása,1,2, Mikhail Ustininb,2, Stanislav Rykunovb,2, Kerry D. Waltona,2, Guilherme M. Rabelloa,2, John Garciaa,2, Anna Boykob,2, and Vyacheslav Sychevb,2 aDepartment of Neuroscience and Physiology, Center for Neuromagnetism, New York University School of Medicine, New York, New York, 10016; and bKeldysh Institute of Applied Mathematics, Russian Academy of Sciences, Moscow, 125047 Russia Contributed by Rodolfo R. Llinás, November 19, 2019 (sent for review August 12, 2019; reviewed by Edgar Garcia-Rill and David Poeppel) A spectroscopic paradigm has been developed that allows the mag- Results netic field emissions generated by the electrical activity in the hu- The results obtained in the present set of functional tomo- man body to be imaged in real time. The growing significance of grams correspond to actual anatomical data, very much to imaging modalities in biology is evident by the almost exponential those obtained by head MRI, or by direct observation in other increase of their use in research, from the molecular to the ecolog- cases. Recordings were made from the head (Fig. 1), heart ical level. The method of analysis described here allows totally non- (Figs. 2 and 3), and several muscle groups (Figs. 4 and 5) at invasive imaging of muscular activity (heart, somatic musculature). rest and during voluntary contraction, or under conditions Such imaging can be obtained without additional methodological where muscles were intrinsically activated during muscle pain steps such as the use of contrast media. (Fig. 5). magnetoencephalography | magnetocardiography | magnetomyograph | Recordings with the Head in the Sensor Helmet. -
Spin Valve Systems for Angle Sensor Applications
Spin Valve Systems for Angle Sensor Applications vom Fachbereich Material- und Geowissenschaften der Technischen Universität Darmstadt genehmigte Dissertation zur Erlangung des akademischen Grades eines Doktors der Ingenieurswissenschaften (Dr.-Ing.) eingereicht von M. Sc. Andrew Johnson aus Cincinnati, Ohio USA Referent: Prof. Dr.-Ing. Horst Hahn Korreferent: Prof. Dr.-Ing. Hartmut Fuess Tag der Einreichung: 25. Juli 2003 Tag der mündlichen Prüfung: 20. Januar 2004 Darmstadt 2004 D17 I Table of Contents 1 Introduction 1 2 Theory 5 2.1 Electrical Resistance and Magnetoresistance ......................................................5 2.2 Anisotropic Magneto Resistance (AMR).............................................................5 2.3 Giant Magneto Resistance (GMR).......................................................................7 2.4 Spin-Dependent Scattering ................................................................................10 2.4.1 Co/Cu Bandgap Structure........................................................................10 2.4.2 Mott Two-Current Model ........................................................................12 2.5 Spin Valve System.............................................................................................13 2.5.1 Magnetoresistance Characteristics of a Spin Valve.................................14 2.5.2 Uniaxial Anisotropy in the Free Layer and Pinned Layer.......................16 2.5.3 Interlayer Coupling in a Spin Valve System ...........................................18