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Ewings RA, Stewart JR, Perring TG, Bewley RI, Le MD, Raspino D, Pooley DE, Škoro G, Waller SP, Zacek D, Smith CA, Riehl-Shaw RC. Upgrade to the MAPS neutron time-of-flight chopper spectrometer. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:035110. [PMID: 30927771 DOI: 10.1063/1.5086255] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/01/2019] [Indexed: 05/23/2023]
Abstract
The MAPS direct geometry time-of-flight chopper spectrometer at the ISIS pulsed neutron and muon source has been in operation since 1999, and its novel use of a large array of position-sensitive neutron detectors paved the way for a later generations of chopper spectrometers around the world. Almost two decades of experience of user operations on MAPS, together with lessons learned from the operation of new generation instruments, led to a decision to perform three parallel upgrades to the instrument. These were to replace the primary beamline collimation with supermirror neutron guides, to install a disk chopper, and to modify the geometry of the poisoning in the water moderator viewed by MAPS. Together, these upgrades were expected to increase the neutron flux substantially, to allow more flexible use of repetition rate multiplication and to reduce some sources of background. Here, we report the details of these upgrades and compare the performance of the instrument before and after their installation as well as to Monte Carlo simulations. These illustrate that the instrument is performing in line with, and in some respects in excess of, expectations. It is anticipated that the improvement in performance will have a significant impact on the capabilities of the instrument. A few examples of scientific commissioning are presented to illustrate some of the possibilities.
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Affiliation(s)
- R A Ewings
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - J R Stewart
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - T G Perring
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - R I Bewley
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - M D Le
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - D Raspino
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - D E Pooley
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - G Škoro
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - S P Waller
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - D Zacek
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - C A Smith
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - R C Riehl-Shaw
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
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2
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Vaghela E, Keshvani MJ, Gadani K, Joshi Z, Boricha H, Asokan K, Venkateshwarlu D, Ganesan V, Shah NA, Solanki PS. Charge transport mechanisms in sol-gel grown La 0.7Pb 0.3MnO 3/LaAlO 3 manganite films. Phys Chem Chem Phys 2017; 19:5163-5176. [PMID: 28140411 DOI: 10.1039/c6cp07730g] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this communication, structural, microstructural, transport and magnetotransport properties are reported for La0.7Pb0.3MnO3/LaAlO3 (LPMO/LAO) manganite films having different thicknesses. All the films were irradiated with 200 MeV Ag+15 swift heavy ions (SHI). Films were grown using the sol-gel method by employing the acetate precursor route. Structural measurements were carried out using the X-ray diffraction (XRD) method at room temperature, while atomic force microscopy (AFM) was performed for the surface morphology. Temperature dependent resistivity under different applied magnetic fields for all the films shows metal to insulator transition at temperature TP. In addition to the metal to insulator transition at TP, the films also exhibit low temperature resistivity upturn behavior. Resistivity, TP and upturn behavior are highly influenced by the film thickness, applied magnetic field and irradiation. To understand the nature of charge transport for the low temperature resistivity behavior and metallic and insulating (semiconducting) regions, various models and mechanisms have been verified and the most suitable mechanism has been found for each region in the resistivity curves. Magnetoresistance (MR) is affected by temperature, film thickness and irradiation. MR behavior has been understood in terms of combined and separate contributions from grains and grain boundaries in the films.
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Affiliation(s)
- Eesh Vaghela
- Department of Physics, Saurashtra University, Rajkot - 360 005, India.
| | - M J Keshvani
- Department of Physics, Saurashtra University, Rajkot - 360 005, India.
| | - Keval Gadani
- Department of Physics, Saurashtra University, Rajkot - 360 005, India.
| | - Zalak Joshi
- Department of Physics, Saurashtra University, Rajkot - 360 005, India.
| | - Hetal Boricha
- Department of Physics, Saurashtra University, Rajkot - 360 005, India.
| | - K Asokan
- UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, 452 001, India
| | - D Venkateshwarlu
- Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi - 110 0067, India
| | - V Ganesan
- Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi - 110 0067, India
| | - N A Shah
- Department of Physics, Saurashtra University, Rajkot - 360 005, India.
| | - P S Solanki
- Department of Physics, Saurashtra University, Rajkot - 360 005, India.
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3
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Lü WM, Saha S, Wang XR, Liu ZQ, Gopinadhan K, Annadi A, Zeng SW, Huang Z, Bao BC, Cong CX, Venkatesan M, Yu T, Coey JMD, Ariando, Venkatesan T. Long-range magnetic coupling across a polar insulating layer. Nat Commun 2016; 7:11015. [PMID: 26980456 PMCID: PMC4799368 DOI: 10.1038/ncomms11015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 02/11/2016] [Indexed: 11/25/2022] Open
Abstract
Magnetic interactions in solids are normally mediated by short-range exchange or weak dipole fields. Here we report a magnetic interaction that can propagate over long distances (∼10 nm) across a polar insulating oxide spacer. Evidence includes oscillations of magnetization, coercivity and field-cooled loop shift with the thickness of LaAlO3 in La0.67Sr0.33MnO3/LaAlO3/SrTiO3 heterostructures. Similar modifications of the hysteresis loop appear when two coupled films of La0.67Sr0.33MnO3 are separated by LaAlO3, or another polar insulator, but they are absent when the oxide spacer layer is nonpolar. The loop shift is attributed to strong spin–orbit coupling and Dzyaloshinskii–Moriya interaction at the interfaces. There is evidence from inelastic light scattering that the polar spacer mediates long-range transmission of orbital magnetization. This coupling mechanism is expected to apply for any conducting ferromagnetic oxide with mixed valence; in view of electron hopping frequency involved, it raises the prospect of terahertz tunability of magnetic coupling. Magnetic interactions in solids are usually short-range or else they involve itinerant electrons. Here, the authors evidence a long-range magnetic coupling mediated by orbital moments in a polar spacer layer of nonmagnetic insulating oxide, with a sign which oscillates with spacer thickness.
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Affiliation(s)
- W M Lü
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore
| | - Surajit Saha
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore.,Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - X Renshaw Wang
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore.,Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Z Q Liu
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore.,Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - K Gopinadhan
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore
| | - A Annadi
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore.,Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - S W Zeng
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore.,Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Z Huang
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore
| | - B C Bao
- Division of Physics and Applied Physics, School of Physical and Mathematical Science, Nanyang Technological University, Singapore 637371, Singapore
| | - C X Cong
- Division of Physics and Applied Physics, School of Physical and Mathematical Science, Nanyang Technological University, Singapore 637371, Singapore
| | - M Venkatesan
- Department of Pure and Applied Physics, Trinity College, Dublin 2, Ireland
| | - T Yu
- Division of Physics and Applied Physics, School of Physical and Mathematical Science, Nanyang Technological University, Singapore 637371, Singapore
| | - J M D Coey
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore.,Department of Pure and Applied Physics, Trinity College, Dublin 2, Ireland
| | - Ariando
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore.,Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - T Venkatesan
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore.,Department of Physics, National University of Singapore, Singapore 117542, Singapore.,Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
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4
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Horiba K, Kitamura M, Yoshimatsu K, Minohara M, Sakai E, Kobayashi M, Fujimori A, Kumigashira H. Isotropic Kink and Quasiparticle Excitations in the Three-Dimensional Perovskite Manganite La_{0.6}Sr_{0.4}MnO_{3}. PHYSICAL REVIEW LETTERS 2016; 116:076401. [PMID: 26943547 DOI: 10.1103/physrevlett.116.076401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Indexed: 06/05/2023]
Abstract
In order to reveal the many-body interactions in three-dimensional perovskite manganites that show colossal magnetoresistance, we performed an in situ angle-resolved photoemission spectroscopy on La_{0.6}Sr_{0.4}MnO_{3} and investigated the behavior of quasiparticles. We observed quasiparticle peaks near the Fermi momentum in both the electron and the hole bands, and clear kinks throughout the entire hole Fermi surface in the band dispersion. This isotropic behavior of quasiparticles and kinks suggests that polaronic quasiparticles produced by the coupling of electrons with Jahn-Teller phonons play an important role in the colossal magnetoresistance properties of the ferromagnetic metallic phase of three-dimensional manganites.
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Affiliation(s)
- Koji Horiba
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801, Japan
| | - Miho Kitamura
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801, Japan
| | - Kohei Yoshimatsu
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801, Japan
- Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Makoto Minohara
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801, Japan
| | - Enju Sakai
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801, Japan
| | - Masaki Kobayashi
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801, Japan
| | - Atsushi Fujimori
- Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hiroshi Kumigashira
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801, Japan
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5
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Zhang J, Ye F, Sha H, Dai P, Fernandez-Baca JA, Plummer EW. Magnons in ferromagnetic metallic manganites. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2007; 19:315204. [PMID: 21694105 DOI: 10.1088/0953-8984/19/31/315204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Ferromagnetic (FM) manganites, a group of likely half-metallic oxides, are of special interest not only because they are a testing ground for the classical double-exchange interaction mechanism for the 'colossal' magnetoresistance, but also because they exhibit an extraordinary arena of emergent phenomena. These emergent phenomena are related to the complexity associated with strong interplay between charge, spin, orbital, and lattice. In this review, we focus on the use of inelastic neutron scattering to study the spin dynamics, mainly the magnon excitations in this class of FM metallic materials. In particular, we discuss the unusual magnon softening and damping near the Brillouin zone boundary in relatively narrow-band compounds with strong Jahn-Teller lattice distortion and charge-orbital correlations. The anomalous behaviours of magnons in these compounds indicate the likelihood of cooperative excitations involving spin and lattice as well as orbital degrees of freedom.
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Affiliation(s)
- Jiandi Zhang
- Department of Physics, Florida International University, Miami, FL 33199, USA
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6
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Senff D, Krüger F, Scheidl S, Benomar M, Sidis Y, Demmel F, Braden M. Spin-wave dispersion in orbitally ordered La1/2Sr3/2MnO4. PHYSICAL REVIEW LETTERS 2006; 96:257201. [PMID: 16907336 DOI: 10.1103/physrevlett.96.257201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Indexed: 05/11/2023]
Abstract
The magnon dispersion in the charge, orbital, and spin ordered phase in La1/2Sr3/2MnO4 has been studied by means of inelastic neutron scattering. We find excellent agreement with a magnetic interaction model based on the CE-type superstructure. The magnetic excitations are dominated by ferromagnetic exchange parameters revealing a nearly one-dimensional character at high energies. The strong ferromagnetic interaction in the charge or orbital ordered phase appears to be essential for the capability of manganites to switch between metallic and insulating phases.
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Affiliation(s)
- D Senff
- II. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln, Germany
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7
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Ye F, Dai P, Fernandez-Baca JA, Sha H, Lynn JW, Kawano-Furukawa H, Tomioka Y, Tokura Y, Zhang J. Evolution of spin-wave excitations in ferromagnetic metallic manganites. PHYSICAL REVIEW LETTERS 2006; 96:047204. [PMID: 16486884 DOI: 10.1103/physrevlett.96.047204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Indexed: 05/06/2023]
Abstract
Neutron scattering results are presented for spin-wave excitations of three ferromagnetic metallic A1-xA'xMnO3 manganites (where A and A' are rare- and alkaline-earth-metal ions), which when combined with previous work elucidate the systematics of the interactions as a function of carrier concentration x, on-site disorder, and strength of the lattice distortion. The long-wavelength spin dynamics show only a very weak dependence across the series. The ratio of fourth to first neighbor exchange (J4/J1) that controls the zone boundary magnon softening changes systematically with x, but does not depend on the other parameters. None of the prevailing models can account for these behaviors.
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Affiliation(s)
- F Ye
- Center for Neutron Scattering, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6393, USA
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8
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Feng SS, Mochena M. Spin-wave softening and Hund's coupling in ferromagnetic manganites. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2005; 17:3895-3901. [PMID: 21690706 DOI: 10.1088/0953-8984/17/25/016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Using a one-orbital model of hole-doped manganites, we show with the help of the Holstein-Primakov transformation that finite Hund's coupling is responsible for the spin-wave softening in the ferromagnetic B-phase manganites. We obtain an analytical result for the spin-wave spectrum for [Formula: see text]. In the limit of infinite Hund's coupling, the spectrum is the conventional nearest-neighbour Heisenberg ferromagnetic spin-wave. The o (t/J(H))-order correction is negative and thus accounts for the softening near the zone boundary.
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9
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Endoh Y, Hiraka H, Tomioka Y, Tokura Y, Nagaosa N, Fujiwara T. Orbital nature of ferromagnetic magnons in manganites. PHYSICAL REVIEW LETTERS 2005; 94:017206. [PMID: 15698129 DOI: 10.1103/physrevlett.94.017206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Indexed: 05/24/2023]
Abstract
Magnon excitation in a ferromagnetic state of Sm(0.55)Sr(0.45)MnO(3) located on the verge of the metal-insulator transition has been studied in terms of the neutron scattering experiment. The anomalous magnon dispersion with the zone-boundary softening is well described by the Heisenberg model with extended exchange coupling constants J(s). In particular the fourth neighbor coupling J(4) is as large as 0.6 times the nearest neighbor one J(1). Theoretical analysis based on the local density approximation + Hubbard U band calculation reveals that this one-dimensional exchange path is due to the (3z(2)-r(2))-type orbital correlation, in sharp contrast to previous proposals.
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Affiliation(s)
- Y Endoh
- Institute for Materials Research, Tohoku University, Katahira, Sendai 980-8577, Japan
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10
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Blundell SJ, Stride JA, Brooks ML, Steer CA, Nair SP, Battle PD, Rosseinsky MJ. The observation of magnetic excitations in a single layered and a bilayered brownmillerite. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2005; 17:99-104. [PMID: 21690672 DOI: 10.1088/0953-8984/17/1/010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We describe the results of an inelastic neutron scattering measurement of the magnetic excitations in SrCaGaMnO(5+δ), a quasi-two-dimensional compound whose structure consists of layers of MnO(6) octahedra separated by layers of GaO(4) tetrahedra (the brownmillerite structure), and Ca(2.5)Sr(0.5)Mn(2)GaO(8), a bilayered brownmillerite. In both materials, a band of magnetic scattering appears below the magnetic ordering temperature which can be associated with magnon excitations. Our measurements allow us to provide an estimate for the intraplane exchange constant in both materials, which we find to be 3.4(4) meV for SrCaGaMnO(5+δ) and 2.2(4) meV for Ca(2.5)Sr(0.5)Mn(2)GaO(8).
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Affiliation(s)
- Stephen J Blundell
- Department of Physics, Clarendon Laboratory, Oxford University, Parks Road, Oxford OX1 3PU, UK
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11
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12
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Perring TG, Adroja DT, Chaboussant G, Aeppli G, Kimura T, Tokura Y. Spectacular doping dependence of interlayer exchange and other results on spin waves in bilayer manganites. PHYSICAL REVIEW LETTERS 2001; 87:217201. [PMID: 11736373 DOI: 10.1103/physrevlett.87.217201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2001] [Indexed: 05/23/2023]
Abstract
We report the measurement of spin waves in the bilayer colossal magnetoresistive manganites La2-2xSr1+2xMn2O7 with x = 0.30, 0.35, and 0.40. For x = 0.35 and 0.40 the entire acoustic and optic dispersion relations are well described by those for a bilayer Heisenberg Hamiltonian with nearest-neighbor exchange only, which is explained together with the spin-wave lifetimes by the double exchange model. The in-plane exchange depends weakly on x, but that between the planes of a bilayer changes by a factor of 4, directly revealing a change from mixed d(3z(2)-r(2)) and d(x(2)-y(2)) orbital character to mostly d(x(2)-y(2)).
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Affiliation(s)
- T G Perring
- ISIS Facility, CLRC Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX, United Kingdom
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13
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Kaplan TA, Mahanti SD, Su YS. Non-Stoner continuum in the double exchange model. PHYSICAL REVIEW LETTERS 2001; 86:3634-3637. [PMID: 11328041 DOI: 10.1103/physrevlett.86.3634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2000] [Indexed: 05/23/2023]
Abstract
Exact diagonalization studies of the double exchange model indicate the existence of continuum states in the single-spin-flip channel that overlap the magnons at very low energies (approximately 10(-2) eV) and extend to high energies (approximately eV). This picture differs dramatically from the prevalent view, where there are the magnons, plus the Stoner continuum at the high-energy scale, with nothing in between. The relevance of these new continuum states to inelastic neutron scattering and optical properties is discussed.
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Affiliation(s)
- T A Kaplan
- Michigan State University, East Lansing, Michigan 48824, USA
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14
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Izyumov YA, Skryabin Y. Double exchange model and the unique properties of the manganites. ACTA ACUST UNITED AC 2001. [DOI: 10.3367/ufnr.0171.200102a.0121] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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15
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Heffner RH, Sonier JE, MacLaughlin DE, Nieuwenhuys GJ, Ehlers G, Mezei F, Cheong SW, Gardner JS, Röder H. Observation of two time scales in the ferromagnetic manganite La1-xCaxMnO3, x approximately 0.3. PHYSICAL REVIEW LETTERS 2000; 85:3285-3288. [PMID: 11019322 DOI: 10.1103/physrevlett.85.3285] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/1999] [Indexed: 05/23/2023]
Abstract
We report new zero-field muon spin relaxation and neutron spin echo measurements in ferromagnetic (FM) (La,Ca)MnO3 which suggest at least two spatially separated regions possessing very different Mn-ion spin dynamics. One region displays diffusive relaxation, "critical slowing down" near T(C) and an increasing volume fraction below T(C), suggesting overdamped FM spin waves below T(C). The second region possesses more slowly fluctuating spins, a linewidth independent of q, and a decreasing volume fraction below T(C). The estimated length scale for the inhomogeneity is <or=30 A.
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Affiliation(s)
- R H Heffner
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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16
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Hamilton JJ, Keatley EL, Ju HL, Raychaudhuri AK, Smolyaninova VN, Greene RL. Low-temperature specific heat of La0.67Ba0.33MnO3 and La0.8Ca0.2MnO3. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:14926-14929. [PMID: 9985538 DOI: 10.1103/physrevb.54.14926] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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