1
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Broussard LJ, Barrow JL, DeBeer-Schmitt L, Dennis T, Fitzsimmons MR, Frost MJ, Gilbert CE, Gonzalez FM, Heilbronn L, Iverson EB, Johnston A, Kamyshkov Y, Kline M, Lewiz P, Matteson C, Ternullo J, Varriano L, Vavra S. Experimental Search for Neutron to Mirror Neutron Oscillations as an Explanation of the Neutron Lifetime Anomaly. Phys Rev Lett 2022; 128:212503. [PMID: 35687456 DOI: 10.1103/physrevlett.128.212503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 03/25/2022] [Accepted: 05/04/2022] [Indexed: 06/15/2023]
Abstract
An unexplained >4σ discrepancy persists between "beam" and "bottle" measurements of the neutron lifetime. A new model proposed that conversions of neutrons n into mirror neutrons n^{'}, part of a dark mirror sector, can increase the apparent neutron lifetime by 1% via a small mass splitting Δm between n and n^{'} inside the 4.6 T magnetic field of the National Institute of Standards and Technology Beam Lifetime experiment. A search for neutron conversions in a 6.6 T magnetic field was performed at the Spallation Neutron Source which excludes this explanation for the neutron lifetime discrepancy.
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Affiliation(s)
- L J Broussard
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J L Barrow
- Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA
| | | | - T Dennis
- Department of Physics and Astronomy, East Tennessee State University, Johnson City, Tennessee 37614, USA
| | - M R Fitzsimmons
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - M J Frost
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - C E Gilbert
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - F M Gonzalez
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - L Heilbronn
- Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - E B Iverson
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - A Johnston
- Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Y Kamyshkov
- Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - M Kline
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - P Lewiz
- Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - C Matteson
- Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - J Ternullo
- Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - L Varriano
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - S Vavra
- Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA
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2
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Wen X, Bao SR, McDonald L, Pierce J, Greene GL, Crow L, Tong X, Mezzacappa A, Glasby R, Guo W, Fitzsimmons MR. Imaging Fluorescence of He_{2}^{*} Excimers Created by Neutron Capture in Liquid Helium II. Phys Rev Lett 2020; 124:134502. [PMID: 32302187 DOI: 10.1103/physrevlett.124.134502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 12/15/2019] [Indexed: 06/11/2023]
Abstract
We show unequivocal evidence for formation of He_{2}^{*} excimers in liquid He II created by ionizing radiation produced through neutron capture. Laser beams induce fluorescence of the excimers. The fluorescence is recorded at a rate of 55.6 Hz by a camera. The location of the fluorescence is determined with an uncertainty of 5 μm. The technique provides an opportunity to record the flow of He_{2}^{*} excimers in a medium with very small viscosity and enables measurement of turbulence around macroscopic liter size objects or vortex matter in three dimensions.
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Affiliation(s)
- X Wen
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
- Shull Wollan Center-A Joint Institute for Neutron Sciences, Oak Ridge, Tennessee 37830, USA
| | - S R Bao
- Mechanical Engineering Department, Florida State University, Tallahassee, Florida 32310, USA
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
| | - L McDonald
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
- Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - J Pierce
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - G L Greene
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - Lowell Crow
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - Xin Tong
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
- Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing 100049, China
- Spallation Neutron Source Science Center, Dongguan 523803, China
| | - A Mezzacappa
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
- Joint Institute for Computational Sciences, Oak Ridge, Tennessee 37830, USA
| | - R Glasby
- Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
- Joint Institute for Computational Sciences, Oak Ridge, Tennessee 37830, USA
| | - W Guo
- Mechanical Engineering Department, Florida State University, Tallahassee, Florida 32310, USA
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
| | - M R Fitzsimmons
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
- Shull Wollan Center-A Joint Institute for Neutron Sciences, Oak Ridge, Tennessee 37830, USA
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3
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Singh S, Freeland JW, Fitzsimmons MR, Jeen H, Biswas A. Composition dependence of charge and magnetic length scales in mixed valence manganite thin films. Sci Rep 2016; 6:29632. [PMID: 27461993 PMCID: PMC4995356 DOI: 10.1038/srep29632] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 06/22/2016] [Indexed: 11/17/2022] Open
Abstract
Mixed-valence manganese oxides present striking properties like the colossal magnetoresistance, metal-insulator transition (MIT) that may result from coexistence of ferromagnetic, metallic and insulating phases. Percolation of such phase coexistence in the vicinity of MIT leads to first-order transition in these manganites. However the length scales over which the electronic and magnetic phases are separated across MIT which appears compelling for bulk systems has been elusive in (La1−yPry)1−xCaxMnO3 films. Here we show the in-plane length scale over which charge and magnetism are correlated in (La0.4Pr0.6)1−xCaxMnO3 films with x = 0.33 and 0.375, across the MIT temperature. We combine electrical transport (resistance) measurements, x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and specular/off-specular x-ray resonant magnetic scattering (XRMS) measurements as a function of temperature to elucidate relationships between electronic, magnetic and morphological structure of the thin films. Using off-specular XRMS we obtained the charge-charge and charge-magnetic correlation length of these LPCMO films across the MIT. We observed different charge-magnetic correlation length for two films which increases below the MIT. The different correlation length shown by two films may be responsible for different macroscopic (transport and magnetic) properties.
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Affiliation(s)
- Surendra Singh
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 India
| | - J W Freeland
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - M R Fitzsimmons
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - H Jeen
- Department of Physics, University of Florida, Gainesville, FL 32611, USA.,Department of Physics, Pusan National University, Busan 609-735, Korea
| | - A Biswas
- Department of Physics, University of Florida, Gainesville, FL 32611, USA
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4
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Jain P, Wang Q, Roldan M, Glavic A, Lauter V, Urban C, Bi Z, Ahmed T, Zhu J, Varela M, Jia QX, Fitzsimmons MR. Synthetic magnetoelectric coupling in a nanocomposite multiferroic. Sci Rep 2015; 5:9089. [PMID: 25766205 PMCID: PMC4357856 DOI: 10.1038/srep09089] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 02/04/2015] [Indexed: 11/09/2022] Open
Abstract
Given the paucity of single phase multiferroic materials (with large ferromagnetic
moment), composite systems seem an attractive solution to realize magnetoelectric
coupling between ferromagnetic and ferroelectric order parameters. Despite
having antiferromagnetic order, BiFeO3 (BFO) has nevertheless been
a key material due to excellent ferroelectric properties at room temperature.
We studied a superlattice composed of 8 repetitions of 6 unit cells of La0.7Sr0.3MnO3
(LSMO) grown on 5 unit cells of BFO. Significant net uncompensated magnetization
in BFO, an insulating superlattice, is demonstrated using polarized neutron
reflectometry. Remarkably, the magnetization enables magnetic field to change
the dielectric properties of the superlattice, which we cite as an example
of synthetic magnetoelectric coupling. Importantly, controlled creation of
magnetic moment in BFO is a much needed path toward design and implementation
of integrated oxide devices for next generation magnetoelectric data storage
platforms.
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Affiliation(s)
- P Jain
- Los Alamos National Laboratory, Los Alamos NM 87545
| | - Q Wang
- Los Alamos National Laboratory, Los Alamos NM 87545
| | - M Roldan
- Universidad Complutense de Madrid, Madrid Spain 28040
| | - A Glavic
- Oak Ridge National Laboratory, Oak Ridge, TN 37831
| | - V Lauter
- Oak Ridge National Laboratory, Oak Ridge, TN 37831
| | - C Urban
- University of California at San Diego, La Jolla CA 92093
| | - Z Bi
- Los Alamos National Laboratory, Los Alamos NM 87545
| | - T Ahmed
- Los Alamos National Laboratory, Los Alamos NM 87545
| | - J Zhu
- Los Alamos National Laboratory, Los Alamos NM 87545
| | - M Varela
- 1] Universidad Complutense de Madrid, Madrid Spain 28040 [2] Oak Ridge National Laboratory, Oak Ridge, TN 37831
| | - Q X Jia
- Los Alamos National Laboratory, Los Alamos NM 87545
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5
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Perez FA, Borisov P, Johnson TA, Stanescu TD, Trappen R, Holcomb MB, Lederman D, Fitzsimmons MR, Aczel AA, Hong T. Phase diagram of a three-dimensional antiferromagnet with random magnetic anisotropy. Phys Rev Lett 2015; 114:097201. [PMID: 25793845 DOI: 10.1103/physrevlett.114.097201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Indexed: 06/04/2023]
Abstract
Three-dimensional antiferromagnets with random magnetic anisotropy (RMA) that have been experimentally studied to date have competing two-dimensional and three-dimensional exchange interactions which can obscure the authentic effects of RMA. The magnetic phase diagram of Fe_{x}Ni_{1-x}F_{2} epitaxial thin films with true random single-ion anisotropy was deduced from magnetometry and neutron scattering measurements and analyzed using mean-field theory. Regions with uniaxial, oblique, and easy-plane anisotropies were identified. A RMA-induced glass region was discovered where a Griffiths-like breakdown of long-range spin order occurs.
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Affiliation(s)
- Felio A Perez
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315, USA
| | - Pavel Borisov
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315, USA
| | - Trent A Johnson
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315, USA
| | - Tudor D Stanescu
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315, USA
| | - Robbyn Trappen
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315, USA
| | - Mikel B Holcomb
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315, USA
| | - David Lederman
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315, USA
| | - M R Fitzsimmons
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Adam A Aczel
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Tao Hong
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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6
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Moon EJ, Colby R, Wang Q, Karapetrova E, Schlepütz CM, Fitzsimmons MR, May SJ. Spatial control of functional properties via octahedral modulations in complex oxide superlattices. Nat Commun 2014; 5:5710. [DOI: 10.1038/ncomms6710] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 10/29/2014] [Indexed: 11/09/2022] Open
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7
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Singh S, Haraldsen JT, Xiong J, Choi EM, Lu P, Yi D, Wen XD, Liu J, Wang H, Bi Z, Yu P, Fitzsimmons MR, MacManus-Driscoll JL, Ramesh R, Balatsky AV, Zhu JX, Jia QX. Induced magnetization in La0.7Sr0.3MnO3/BiFeO3 superlattices. Phys Rev Lett 2014; 113:047204. [PMID: 25105651 DOI: 10.1103/physrevlett.113.047204] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Indexed: 06/03/2023]
Abstract
Using polarized neutron reflectometry, we observe an induced magnetization of 75 ± 25 kA/m at 10 K in a La(0.7)Sr(0.3)MnO(3) (LSMO)/BiFeO(3) superlattice extending from the interface through several atomic layers of the BiFeO(3) (BFO). The induced magnetization in BFO is explained by density functional theory, where the size of band gap of BFO plays an important role. Considering a classical exchange field between the LSMO and BFO layers, we further show that magnetization is expected to extend throughout the BFO, which provides a theoretical explanation for the results of the neutron scattering experiment.
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Affiliation(s)
- Surendra Singh
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA and Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400085, India
| | - J T Haraldsen
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA and Department of Physics and Astronomy, James Madison University, Harrisonburg, Virginia 22807, USA
| | - J Xiong
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA and State Key Lab of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610051, China
| | - E M Choi
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, United Kingdom
| | - P Lu
- Sandia National Laboratory, Albuquerque, New Mexico 87185, USA
| | - D Yi
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720, USA
| | - X-D Wen
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J Liu
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720, USA
| | - H Wang
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - Z Bi
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - P Yu
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720, USA
| | - M R Fitzsimmons
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J L MacManus-Driscoll
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, United Kingdom
| | - R Ramesh
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720, USA
| | - A V Balatsky
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Jian-Xin Zhu
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Q X Jia
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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8
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Cuellar FA, Liu YH, Salafranca J, Nemes N, Iborra E, Sanchez-Santolino G, Varela M, Garcia Hernandez M, Freeland JW, Zhernenkov M, Fitzsimmons MR, Okamoto S, Pennycook SJ, Bibes M, Barthélémy A, te Velthuis SGE, Sefrioui Z, Leon C, Santamaria J. Reversible electric-field control of magnetization at oxide interfaces. Nat Commun 2014; 5:4215. [PMID: 24953219 DOI: 10.1038/ncomms5215] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 05/27/2014] [Indexed: 11/09/2022] Open
Abstract
Electric-field control of magnetism has remained a major challenge which would greatly impact data storage technology. Although progress in this direction has been recently achieved, reversible magnetization switching by an electric field requires the assistance of a bias magnetic field. Here we take advantage of the novel electronic phenomena emerging at interfaces between correlated oxides and demonstrate reversible, voltage-driven magnetization switching without magnetic field. Sandwiching a non-superconducting cuprate between two manganese oxide layers, we find a novel form of magnetoelectric coupling arising from the orbital reconstruction at the interface between interfacial Mn spins and localized states in the CuO2 planes. This results in a ferromagnetic coupling between the manganite layers that can be controlled by a voltage. Consequently, magnetic tunnel junctions can be electrically toggled between two magnetization states, and the corresponding spin-dependent resistance states, in the absence of a magnetic field.
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Affiliation(s)
- F A Cuellar
- 1] GFMC, Departamento Fisica Aplicada III, Universidad Complutense Madrid, 28040 Madrid, Spain [2]
| | - Y H Liu
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - J Salafranca
- 1] GFMC, Departamento Fisica Aplicada III, Universidad Complutense Madrid, 28040 Madrid, Spain [2] Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - N Nemes
- GFMC, Departamento Fisica Aplicada III, Universidad Complutense Madrid, 28040 Madrid, Spain
| | - E Iborra
- GMME Departamento de Tecnologia Electronica, ETSIT, Universidad Politecnica de Madrid, 28040 Madrid, Spain
| | - G Sanchez-Santolino
- 1] GFMC, Departamento Fisica Aplicada III, Universidad Complutense Madrid, 28040 Madrid, Spain [2] Laboratorio de Heteroestructuras con aplicación en Spintronica, Unidad Asociada CSIC/Universidad Complutense Madrid, Sor Juana Inés de la Cruz, 3, ES-28049 Madrid, Spain
| | - M Varela
- 1] GFMC, Departamento Fisica Aplicada III, Universidad Complutense Madrid, 28040 Madrid, Spain [2] Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M Garcia Hernandez
- 1] Laboratorio de Heteroestructuras con aplicación en Spintronica, Unidad Asociada CSIC/Universidad Complutense Madrid, Sor Juana Inés de la Cruz, 3, ES-28049 Madrid, Spain [2] Instituto de Ciencia de Materiales de Madrid, 28049 Madrid, Spain
| | - J W Freeland
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - M Zhernenkov
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - M R Fitzsimmons
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - S Okamoto
- Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - S J Pennycook
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, USA
| | - M Bibes
- 1] Unité Mixte de Physique CNRS/Thales, 1 avenue Augustin Fresnel, Campus de l'Ecole Polytechnique, 91767 Palaiseau, France [2] Université Paris-Sud, 91905 Orsay, France
| | - A Barthélémy
- 1] Unité Mixte de Physique CNRS/Thales, 1 avenue Augustin Fresnel, Campus de l'Ecole Polytechnique, 91767 Palaiseau, France [2] Université Paris-Sud, 91905 Orsay, France
| | - S G E te Velthuis
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Z Sefrioui
- 1] GFMC, Departamento Fisica Aplicada III, Universidad Complutense Madrid, 28040 Madrid, Spain [2] Laboratorio de Heteroestructuras con aplicación en Spintronica, Unidad Asociada CSIC/Universidad Complutense Madrid, Sor Juana Inés de la Cruz, 3, ES-28049 Madrid, Spain
| | - C Leon
- 1] GFMC, Departamento Fisica Aplicada III, Universidad Complutense Madrid, 28040 Madrid, Spain [2] Laboratorio de Heteroestructuras con aplicación en Spintronica, Unidad Asociada CSIC/Universidad Complutense Madrid, Sor Juana Inés de la Cruz, 3, ES-28049 Madrid, Spain
| | - J Santamaria
- 1] GFMC, Departamento Fisica Aplicada III, Universidad Complutense Madrid, 28040 Madrid, Spain [2] Laboratorio de Heteroestructuras con aplicación en Spintronica, Unidad Asociada CSIC/Universidad Complutense Madrid, Sor Juana Inés de la Cruz, 3, ES-28049 Madrid, Spain
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9
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Washington AL, Li X, Schofield AB, Hong K, Fitzsimmons MR, Dalgliesh R, Pynn R. Inter-particle correlations in a hard-sphere colloidal suspension with polymer additives investigated by Spin Echo Small Angle Neutron Scattering (SESANS). Soft Matter 2014; 10:3016-3026. [PMID: 24695952 DOI: 10.1039/c3sm53027b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Using a neutron scattering technique that measures a statistically-averaged density correlation function in real space rather than the conventional reciprocal-space structure factor, we have measured correlations between poly(methyl-methacrylate) (PMMA) colloidal particles of several sizes suspended in decalin. The new method, called Spin Echo Small Angle Neutron Scattering (SESANS) provides accurate information about particle composition, including the degree of solvent penetration into the polymer brush grafted on to the PMMA spheres to prevent aggregation. It confirms for particles, between 85 nm and 150 nm in radius that inter-particle correlations closely follow the Percus-Yevick hard-sphere model when the colloidal volume-fraction is between 30% and 50% provided the volume-fraction is used as a fitted parameter. No particle aggregation occurs in these systems. When small amounts of polystyrene are added as a depletant to a concentrated suspension of PMMA particles, short-range clustering of the particles occurs and there is an increase in the frequency of near-neighbor contacts. Within a small range of depletant concentration, near-neighbor correlations saturate and large aggregates with power law density correlations are formed. SESANS clearly separates the short- and long-range correlations and shows that, in this case, the power-law correlations are visible for inter-particle distances larger than roughly two particle diameters. In some cases, aggregate sizes are within our measurement window, which can extend out to 16 microns in favorable cases. We discuss the advantages of SESANS for measurements of the structure of concentrated colloidal systems and conclude that the method offers several important advantages.
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Affiliation(s)
- A L Washington
- Center for the Exploration of Energy and Matter, Indiana University, Bloomington, Indiana, USA.
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10
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Liu Y, Cuellar FA, Sefrioui Z, Freeland JW, Fitzsimmons MR, Leon C, Santamaria J, te Velthuis SGE. Emergent spin filter at the interface between ferromagnetic and insulating layered oxides. Phys Rev Lett 2013; 111:247203. [PMID: 24483696 DOI: 10.1103/physrevlett.111.247203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Indexed: 06/03/2023]
Abstract
We report a strong effect of interface-induced magnetization on the transport properties of magnetic tunnel junctions consisting of ferromagnetic manganite La0.7Ca0.3MnO3 and insulating cuprate PrBa2Cu3O7. Contrary to the typically observed steady increase of the tunnel magnetoresistance with decreasing temperature, this system exhibits a sudden anomalous decrease at low temperatures. Interestingly, this anomalous behavior can be attributed to the competition between the positive spin polarization of the manganite contacts and the negative spin-filter effect from the interface-induced Cu magnetization.
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Affiliation(s)
- Yaohua Liu
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - F A Cuellar
- GFMC, Departamento de Fisica Aplicada III, Universidad Complutense de Madrid, Campus Moncloa, ES-28040 Madrid, Spain
| | - Z Sefrioui
- GFMC, Departamento de Fisica Aplicada III, Universidad Complutense de Madrid, Campus Moncloa, ES-28040 Madrid, Spain
| | - J W Freeland
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - M R Fitzsimmons
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - C Leon
- GFMC, Departamento de Fisica Aplicada III, Universidad Complutense de Madrid, Campus Moncloa, ES-28040 Madrid, Spain
| | - J Santamaria
- GFMC, Departamento de Fisica Aplicada III, Universidad Complutense de Madrid, Campus Moncloa, ES-28040 Madrid, Spain
| | - S G E te Velthuis
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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11
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Grutter AJ, Yang H, Kirby BJ, Fitzsimmons MR, Aguiar JA, Browning ND, Jenkins CA, Arenholz E, Mehta VV, Alaan US, Suzuki Y. Interfacial ferromagnetism in LaNiO3/CaMnO3 superlattices. Phys Rev Lett 2013; 111:087202. [PMID: 24010469 DOI: 10.1103/physrevlett.111.087202] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Indexed: 06/02/2023]
Abstract
We observe interfacial ferromagnetism in superlattices of the paramagnetic metal LaNiO3 and the antiferromagnetic insulator CaMnO3. LaNiO3 exhibits a thickness dependent metal-insulator transition and we find the emergence of ferromagnetism to be coincident with the conducting state of LaNiO3. That is, only superlattices in which the LaNiO3 layers are metallic exhibit ferromagnetism. Using several magnetic probes, we have determined that the ferromagnetism arises in a single unit cell of CaMnO3 at the interface. Together these results suggest that ferromagnetism can be attributed to a double exchange interaction among Mn ions mediated by the adjacent itinerant metal.
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Affiliation(s)
- A J Grutter
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA and Geballe Laboratory for Advanced Materials and Department of Applied Physics, Stanford University, Stanford, California 94305, USA
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12
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He C, Grutter AJ, Gu M, Browning ND, Takamura Y, Kirby BJ, Borchers JA, Kim JW, Fitzsimmons MR, Zhai X, Mehta VV, Wong FJ, Suzuki Y. Interfacial ferromagnetism and exchange bias in CaRuO3/CaMnO3 superlattices. Phys Rev Lett 2012; 109:197202. [PMID: 23215420 DOI: 10.1103/physrevlett.109.197202] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 09/03/2012] [Indexed: 06/01/2023]
Abstract
We have found ferromagnetism in epitaxially grown superlattices of CaRuO(3)/CaMnO(3) that arises in one unit cell at the interface. Scanning transmission electron microscopy and electron energy loss spectroscopy indicate that the difference in magnitude of the Mn valence states between the center of the CaMnO(3) layer and the interface region is consistent with double exchange interaction among the Mn ions at the interface. Polarized neutron reflectivity and the CaMnO(3) thickness dependence of the exchange bias field together indicate that the interfacial ferromagnetism is only limited to one unit cell of CaMnO(3) at each interface. The interfacial moment alternates between the 1 μ(B)/interface Mn ion for even CaMnO(3) layers and the 0.5 μ(B)/interface Mn ion for odd CaMnO(3) layers. This modulation, combined with the exchange bias, suggests the presence of a modulating interlayer coupling between neighboring ferromagnetic interfaces via the antiferromagnetic CaMnO(3) layers.
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Affiliation(s)
- C He
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
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13
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Liu Y, Visani C, Nemes NM, Fitzsimmons MR, Zhu LY, Tornos J, Garcia-Hernandez M, Zhernenkov M, Hoffmann A, Leon C, Santamaria J, te Velthuis SGE. Effect of interface-induced exchange fields on cuprate-manganite spin switches. Phys Rev Lett 2012; 108:207205. [PMID: 23003184 DOI: 10.1103/physrevlett.108.207205] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Indexed: 06/01/2023]
Abstract
We examine the anomalous inverse spin switch behavior in La0.7Ca0.3MnO3(LCMO)/YBa2Cu3O7-δ (YBCO)/LCMO trilayers by combined transport studies and polarized neutron reflectometry. Measuring magnetization profiles and magnetoresistance in an in-plane rotating magnetic field, we prove that, contrary to many accepted theoretical scenarios, the relative orientation between the two LCMO's magnetizations is not sufficient to determine the magnetoresistance. Rather the field dependence of magnetoresistance is explained by the interplay between the applied magnetic field and the (exponential tail of the) induced exchange field in YBCO, the latter originating from the electronic reconstruction at the LCMO/YBCO interfaces.
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Affiliation(s)
- Yaohua Liu
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
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14
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Singh S, Fitzsimmons MR, Lookman T, Thompson JD, Jeen H, Biswas A, Roldan MA, Varela M. Magnetic nonuniformity and thermal hysteresis of magnetism in a manganite thin film. Phys Rev Lett 2012; 108:077207. [PMID: 22401251 DOI: 10.1103/physrevlett.108.077207] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 12/14/2011] [Indexed: 05/31/2023]
Abstract
We measured the chemical and magnetic depth profiles of a single crystalline (La(1-x)Pr(x))(1-y)Ca(y)MnO(3-δ) (x=0.52±0.05, y=0.23±0.04, δ=0.14±0.10) film grown on a NdGaO(3) substrate using x-ray reflectometry, electron microscopy, electron energy-loss spectroscopy, and polarized neutron reflectometry. Our data indicate that the film exhibits coexistence of different magnetic phases as a function of depth. The magnetic depth profile is correlated with a variation of chemical composition with depth. The thermal hysteresis of ferromagnetic order in the film suggests a first-order ferromagnetic transition at low temperatures.
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Affiliation(s)
- Surendra Singh
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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15
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Fitzsimmons MR, Hengartner NW, Singh S, Zhernenkov M, Bruno FY, Santamaria J, Brinkman A, Huijben M, Molegraaf HJA, de la Venta J, Schuller IK. Upper limit to magnetism in LaAlO3/SrTiO3 heterostructures. Phys Rev Lett 2011; 107:217201. [PMID: 22181916 DOI: 10.1103/physrevlett.107.217201] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Indexed: 05/31/2023]
Abstract
Using polarized neutron reflectometry we measured the neutron spin-dependent reflectivity from four LaAlO(3)/SrTiO(3) superlattices. Our results imply that the upper limit for the magnetization averaged over the lateral dimensions of the sample induced by an 11 T magnetic field at 1.7 K is less than 2 G. SQUID magnetometry of the neutron superlattice samples sporadically finds an enhanced moment, possibly due to experimental artifacts. These observations set important restrictions on theories which imply a strongly enhanced magnetism at the interface between LaAlO(3) and SrTiO(3).
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Ashkar R, de Haan VO, van Well AA, Dalgliesh R, Plomp J, Fitzsimmons MR, Schaich WL, Pynn R. Comparison of dynamical theory and phase-object approximation for neutron scattering from periodic structures. J Appl Crystallogr 2011. [DOI: 10.1107/s0021889811032730] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Dynamical theory (DT) calculations have been successfully developed to explain neutron spin-echo resolved grazing-incidence scattering from diffraction gratings. The theory, without any adjustable parameters, has been shown in previous publications to accurately reproduce the sensitivity of the spin-echo polarization signal to sample specifications and scattering geometry. The phase-object approximation (POA), which is computationally less demanding than the DT, has also been used to analyze neutron spin-echo polarization data obtained from diffraction gratings. In this paper, POA and DT calculations are compared for neutron scattering from various diffraction gratings in different geometrical settings. POA gives a good description of the data for transmission cases, where the neutron beam is incident at large angles to the average grating surface. However, for the grazing-incidence reflection cases that were studied, the POA does not fit the data using the independently determined dimensions of the measured gratings. On the other hand, the good agreement between dynamical theory and the data from gratings with known profiles paves the way for its use to extract profile information from periodic samples with unknown structures.
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17
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Ashkar R, Stonaha P, Washington AL, Shah VR, Fitzsimmons MR, Maranville B, Majkrzak CF, Lee WT, Schaich WL, Pynn R. Dynamical theory calculations of spin-echo resolved grazing-incidence scattering from a diffraction grating. J Appl Crystallogr 2010. [DOI: 10.1107/s0021889810010642] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Neutrons scattered or reflected from a diffraction grating are subject to a periodic potential analogous to the potential experienced by electrons within a crystal. Hence, the wavefunction of the neutrons can be expanded in terms of Bloch waves and a dynamical theory can be applied to interpret the scattering phenomenon. In this paper, a dynamical theory is used to calculate the results of neutron spin-echo resolved grazing-incidence scattering (SERGIS) from a silicon diffraction grating with a rectangular profile. The calculations are compared with SERGIS measurements made on the same grating at two neutron sources: a pulsed source and a continuous wave source. In both cases, the spin-echo polarization, studied as a function of the spin-echo length, peaks at integer multiples of the grating period but there are some differences between the two sets of data. The dynamical theory explains the differences and gives a good account of both sets of results.
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18
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Leighton C, Hoffmann A, Fitzsimmons MR, Nogués J, Schuller IK. Deposition of epitaxial α-Fe2O3 layers for exchange bias studies by reactive dc magnetron sputtering. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/13642810110061501] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Affiliation(s)
- C. Leighton
- a Physics Department , University of California , San Diego , La Jolla California , 92093-0319 , USA
- d Department of Chemical Engineering and Materials Science , University of Minnesota , Minneapolis 55455 , USA
| | - A. Hoffmann
- b Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , USA
| | - M. R. Fitzsimmons
- a Physics Department , University of California , San Diego , La Jolla California , 92093-0319 , USA
| | - J. Nogués
- c Departament de Física , Universitat Autónoma de Barcelona , 08193 , Bellaterra , Spain
| | - Ivan K. Schuller
- a Physics Department , University of California , San Diego , La Jolla California , 92093-0319 , USA
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Bao W, Qiu Y, Huang Q, Green MA, Zajdel P, Fitzsimmons MR, Zhernenkov M, Chang S, Fang M, Qian B, Vehstedt EK, Yang J, Pham HM, Spinu L, Mao ZQ. Tunable (deltapi, deltapi)-type antiferromagnetic order in alpha-Fe(Te,Se) superconductors. Phys Rev Lett 2009; 102:247001. [PMID: 19659037 DOI: 10.1103/physrevlett.102.247001] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Indexed: 05/25/2023]
Abstract
The new alpha-Fe(Te,Se) superconductors share the common iron building block and ferminology with the LaFeAsO and BaFe(2)As(2) families of superconductors. In contrast with the predicted commensurate spin-density-wave order at the nesting wave vector (pi, 0), a completely different magnetic order with a composition tunable propagation vector (deltapi, deltapi) was determined for the parent compound Fe_{1+y}Te in this powder and single-crystal neutron diffraction study. The new antiferromagnetic order survives as a short-range one even in the highest T_{C} sample. An alternative to the prevailing nesting Fermi surface mechanism is required to understand the latest family of ferrous superconductors.
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Affiliation(s)
- Wei Bao
- Department of Physics, Renmin University of China, Beijing 100872, China.
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20
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Pynn R, Fitzsimmons MR, Lee WT, Shah VR, Washington AL, Stonaha P, Littrell K. Spin echo scattering angle measurement at a pulsed neutron source. J Appl Crystallogr 2008. [DOI: 10.1107/s0021889808020402] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Two experiments were performed to adapt spin echo scattering angle measurement (SESAME) to pulsed neutron sources. SESAME is an interferometric method that provides enhanced resolution of neutron scattering angles without the loss of neutron intensity that results when collimation is used to improve angular resolution. The method uses the neutron equivalent of optical wave plates to produce a phase difference between the two neutron spin components of a polarized neutron beam. Because the wave plate is inclined to the neutron beam, this phase difference depends sensitively on the trajectory of the neutron. In the absence of a sample, a second wave plate, which is parallel to the first, undoes the phase difference introduced by the first wave plate, producing a polarization identical to that of the incident neutron beam. When a scattering sample is placed between the two neutron wave plates, the cancellation of the phase difference between the neutron spin states is not perfect and the resulting neutron-beam polarization is a measure of the distribution of scattering angles. In the first experiment, thin (30 and 60 µm-thick) magnetized Permalloy films were used as neutron wave plates. In a second experiment, current-carrying solenoids with triangular cross sections were used as birefringent prisms for neutrons. The arrangement of these prisms was such that they mimicked the effect of the neutron wave plates in the first experiment. In both experiments, correlation lengths in the scattering sample of about 1000 Å were probed using very simple and inexpensive equipment. These experiments brought to light a number of advantages and disadvantages of implementing SESAME at pulsed neutron sources and provided insights into the relative merits of SESAME and traditional small-angle neutron scattering.
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Bhattacharya A, May SJ, te Velthuis SGE, Warusawithana M, Zhai X, Jiang B, Zuo JM, Fitzsimmons MR, Bader SD, Eckstein JN. Metal-insulator transition and its relation to magnetic structure in (LaMnO3)2n/(SrMnO3)n superlattices. Phys Rev Lett 2008; 100:257203. [PMID: 18643699 DOI: 10.1103/physrevlett.100.257203] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2007] [Indexed: 05/26/2023]
Abstract
Superlattices of (LaMnO3){2n}/(SrMnO3){n} (1<or=n<or=5), composed of the gapped insulators LaMnO3 and SrMnO3, undergo a metal-insulator transition as a function of n, being metallic for n<or=2 and insulating for n>or=3. Measurements of transport, magnetization, and polarized neutron reflectivity reveal that the ferromagnetism is relatively uniform in the metallic state, and is strongly modulated in the insulating state, being high in LaMnO3 and suppressed in SrMnO3. The modulation is consistent with a Mott transition driven by the proximity between the (LaMnO3)/(SrMnO3) interfaces. The insulating state for n>or=3 obeys variable range hopping at low temperatures. We suggest that this is due to states at the Fermi level that emerge at the (LaMnO3)/(SrMnO3) interfaces and are localized by disorder.
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Affiliation(s)
- A Bhattacharya
- Materials Science Division and Argonne National Laboratory, Argonne, Illinois 60439, USA.
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22
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Littrell KC, te Velthuis SGE, Felcher GP, Park S, Kirby BJ, Fitzsimmons MR. Magnetic compound refractive lens for focusing and polarizing cold neutron beams. Rev Sci Instrum 2007; 78:035101. [PMID: 17411211 DOI: 10.1063/1.2709844] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Biconcave cylindrical lenses are used to focus beams of x rays or neutrons using the refractive properties of matter. In the case of neutrons, the refractive properties of magnetic induction can similarly focus and simultaneously polarize the neutron beam without the concomitant attenuation of matter. This concept of a magnetic refractive lens was tested using a compound lens consisting of 99 pairs of cylindrical permanent magnets. The assembly successfully focused the intensity of a white beam of cold neutrons of one spin state at the detector, while defocusing the other. This experiment confirmed that a lens of this nature may boost the intensity locally by almost an order of magnitude and create a polarized beam. An estimate of the performance of a more practically dimensioned device suitable for incorporation in reflectometers and slit-geometry small angle scattering instruments is given.
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Affiliation(s)
- K C Littrell
- Argonne National Laboratory, Argonne, IL 60439, USA
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Affiliation(s)
- J. A. Eastman
- a Argonne National Laboratory, Materials Science Division , Argonne , Illinois , 60439 , USA
| | - M. R. Fitzsimmons
- a Argonne National Laboratory, Materials Science Division , Argonne , Illinois , 60439 , USA
| | - L. J. Thompson
- b Los Alamos National Laboratory, LANSCE , Los Alamos , New Mexico , 87545 , USA
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24
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Roy S, Fitzsimmons MR, Park S, Dorn M, Petracic O, Roshchin IV, Li ZP, Batlle X, Morales R, Misra A, Zhang X, Chesnel K, Kortright JB, Sinha SK, Schuller IK. Depth profile of uncompensated spins in an exchange bias system. Phys Rev Lett 2005; 95:047201. [PMID: 16090835 DOI: 10.1103/physrevlett.95.047201] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2005] [Indexed: 05/03/2023]
Abstract
We have used the unique spatial sensitivity of polarized neutron and soft x-ray beams in reflection geometry to measure the depth dependence of magnetization across the interface between a ferromagnet and an antiferromagnet. The net uncompensated magnetization near the interface responds to applied field, while uncompensated spins in the antiferromagnet bulk are pinned, thus providing a means to establish exchange bias.
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Affiliation(s)
- S Roy
- Department of Physics, University of California at San Diego, La Jolla, California 92093, USA
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Leighton C, Fitzsimmons MR, Yashar P, Hoffmann A, Nogués J, Dura J, Majkrzak CF, Schuller IK. Two-stage magnetization reversal in exchange biased bilayers. Phys Rev Lett 2001; 86:4394-4397. [PMID: 11328183 DOI: 10.1103/physrevlett.86.4394] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2000] [Indexed: 05/23/2023]
Abstract
MnF(2)/Fe bilayers exhibit asymmetric magnetization reversal that occurs by coherent rotation on one side of the loop and by nucleation and propagation of domain walls on the other side of the loop. Here, we show by polarized neutron reflectometry, magnetization, and magnetotransport measurements that for samples with good crystalline "quality" the rotation is a two-stage process, due to coherent rotation to a stable state perpendicular to the cooling field direction. The result is remarkably asymmetrically shaped hysteresis loops.
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Affiliation(s)
- C Leighton
- Physics Department, University of California-San Diego, La Jolla, California 92093-0319. USA
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26
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Fitzsimmons MR, Yashar P, Leighton C, Schuller IK, Nogues J, Majkrzak CF, Dura JA. Asymmetric magnetization reversal in exchange-biased hysteresis loops. Phys Rev Lett 2000; 84:3986-3989. [PMID: 11019256 DOI: 10.1103/physrevlett.84.3986] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/1999] [Indexed: 05/23/2023]
Abstract
Polarized neutron reflectometry is used to probe the in-plane projection of the net-magnetization vector M--> of polycrystalline Fe films exchange coupled to twinned (110) MnF (2) or FeF (2) antiferromagnetic (AF) layers. The magnetization reversal mechanism depends upon the orientation of the cooling field with respect to the twinned microstructure of the AF, and whether the applied field is increased to (or decreased from) a positive saturating field; i.e. , the magnetization reversal is asymmetric. The reversal of the sample magnetization from one saturated state to the other occurs via either domain wall motion or magnetization rotation on opposite sides of the same hysteresis loop.
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Affiliation(s)
- MR Fitzsimmons
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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27
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Mashl RJ, Gro/nbech-Jensen N, Fitzsimmons MR, Lütt M, Li D. Theoretical and experimental adsorption studies of polyelectrolytes on an oppositely charged surface. J Chem Phys 1999. [DOI: 10.1063/1.477834] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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28
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Li D, Lütt M, Fitzsimmons MR, Synowicki R, Hawley ME, Brown GW. Preparation, Characterization, and Properties of Mixed Organic and Polymeric Self-Assembled Multilayers. J Am Chem Soc 1998. [DOI: 10.1021/ja981232p] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- DeQuan Li
- Contribution from the Chemical Science and Technology Division, Manuel Lujan Jr. Neutron Scattering Center, and Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and J. A. Woollam Co., Inc., 650 J Street, Suite 39, Lincoln, Nebraska 68508
| | - M. Lütt
- Contribution from the Chemical Science and Technology Division, Manuel Lujan Jr. Neutron Scattering Center, and Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and J. A. Woollam Co., Inc., 650 J Street, Suite 39, Lincoln, Nebraska 68508
| | - M. R. Fitzsimmons
- Contribution from the Chemical Science and Technology Division, Manuel Lujan Jr. Neutron Scattering Center, and Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and J. A. Woollam Co., Inc., 650 J Street, Suite 39, Lincoln, Nebraska 68508
| | - R. Synowicki
- Contribution from the Chemical Science and Technology Division, Manuel Lujan Jr. Neutron Scattering Center, and Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and J. A. Woollam Co., Inc., 650 J Street, Suite 39, Lincoln, Nebraska 68508
| | - M. E. Hawley
- Contribution from the Chemical Science and Technology Division, Manuel Lujan Jr. Neutron Scattering Center, and Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and J. A. Woollam Co., Inc., 650 J Street, Suite 39, Lincoln, Nebraska 68508
| | - G. W. Brown
- Contribution from the Chemical Science and Technology Division, Manuel Lujan Jr. Neutron Scattering Center, and Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and J. A. Woollam Co., Inc., 650 J Street, Suite 39, Lincoln, Nebraska 68508
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Affiliation(s)
- M. Lütt
- Manuel Lujan Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
| | - M. R. Fitzsimmons
- Manuel Lujan Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
| | - DeQuan Li
- Chemical Science and Technology Division (CST-4), Los Alamos National Laboratory, Los Alamos, New Mexico 87545
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Fitzsimmons MR, Eastman JA, Thompson LJ. Roles of grain size and strain on antiferromagnetic order in nanocrystalline chromium. Phys Rev B Condens Matter 1994; 50:5600-5608. [PMID: 9976904 DOI: 10.1103/physrevb.50.5600] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Fitzsimmons MR, Eastman JA, Robinson RA, Lawson AC, Thompson JD, Movshovich R, Satti J. Magnetic order in nanocrystalline Cr and suppression of antiferromagnetism in bcc Cr. Phys Rev B Condens Matter 1993; 48:8245-8252. [PMID: 10007015 DOI: 10.1103/physrevb.48.8245] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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32
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Burkel E, Fitzsimmons MR. X-ray and neutron reflectivity studies of twist grain boundaries and phase boundaries. Acta Crystallogr A 1993. [DOI: 10.1107/s0108767378091059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Fitzsimmons MR, Eastman JA, Müller-Stach M, Wallner G. Structural characterization of nanometer-sized crystalline Pd by x-ray-diffraction techniques. Phys Rev B Condens Matter 1991; 44:2452-2460. [PMID: 9999814 DOI: 10.1103/physrevb.44.2452] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Fitzsimmons MR, Burkel E, Sass SL. Experimental measurement of the thermal displacive properties of a large-angle twist grain boundary in gold. Phys Rev Lett 1988; 61:2237-2240. [PMID: 10039023 DOI: 10.1103/physrevlett.61.2237] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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