1
|
Winn BL, Broholm C, Bird MD, Haberl B, Granroth GE, Katsaras J. A flexible neutron spectrometer concept with a new ultra-high field steady-state vertical-bore magnet. Rev Sci Instrum 2022; 93:123903. [PMID: 36586946 DOI: 10.1063/5.0122934] [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: 08/26/2022] [Accepted: 11/14/2022] [Indexed: 06/17/2023]
Abstract
The proposed facility explores materials under ultra-high magnetic fields. By combining the power of high fields to tune materials and of neutron scattering to probe the resulting changes down to the atomic scale, this facility will enable transformative progress in the study of quantum materials and is named for the "TITAN" subset of Greek gods to reflect this transformation. TITAN will offer DC magnetic fields up to at least 20 T. Exploiting the record brightness and bandwidth of the Second Target Station at the Spallation Neutron Source, TITAN will probe atomic-scale responses through high efficiency neutron spectroscopy up to 80 meV energy transfer, high resolution diffraction, and small angle neutron scattering. Focusing neutron optics will maximize flux on accurately positioned samples, while radial collimation and optimized shielding and detection strategies will minimize backgrounds.
Collapse
Affiliation(s)
- B L Winn
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - C Broholm
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - M D Bird
- Magnet Science and Technology Division, National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
| | - B Haberl
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - G E Granroth
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - J Katsaras
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| |
Collapse
|
2
|
Haberl B, Quirinale DG, Li CW, Granroth GE, Nojiri H, Donnelly ME, Ushakov SV, Boehler R, Winn BL. Multi-extreme conditions at the Second Target Station. Rev Sci Instrum 2022; 93:083907. [PMID: 36050043 DOI: 10.1063/5.0093065] [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: 03/25/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
Three concepts for the application of multi-extreme conditions under in situ neutron scattering are described here. The first concept is a neutron diamond anvil cell made from a non-magnetic alloy. It is shrunk in size to fit existing magnets and future magnet designs and is designed for best pressure stability upon cooling. This will allow for maximum pressures above 10 GPa to be applied simultaneously with (steady-state) high magnetic field and (ultra-)low temperature. Additionally, an implementation of miniature coils for neutron diamond cells is presented for pulsed-field applications. The second concept presents a set-up for laser-heating a neutron diamond cell using a defocused CO2 laser. Cell, anvil, and gasket stability will be achieved through stroboscopic measurements and maximum temperatures of 1500 K are anticipated at pressures to the megabar. The third concept presents a hybrid levitator to enable measurements of solids and liquids at temperatures in excess of 4000 K. This will be accomplished by a combination of bulk induction and surface laser heating and hyperbaric conditions to reduce evaporation rates. The potential for deployment of these multi-extreme environments within this first instrument suite of the Second Target Station is described with a special focus on VERDI, PIONEER, CENTAUR, and CHESS. Furthermore, considerations for deployment on future instruments, such as the one proposed as TITAN, are discussed. Overall, the development of these multi-extremes at the Second Target Station, but also beyond, will be highly advantageous for future experimentation and will give access to parameter space previously not possible for neutron scattering.
Collapse
Affiliation(s)
- B Haberl
- Neutron Scattering Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - D G Quirinale
- Neutron Scattering Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - C W Li
- Materials Science and Engineering/Mechanical Engineering, University of California, Riverside, California 92521, USA
| | - G E Granroth
- Neutron Scattering Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - H Nojiri
- Insitute for Materials Research Tohoku University, Sendai, Japan
| | - M-E Donnelly
- Neutron Scattering Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - S V Ushakov
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85281, USA
| | - R Boehler
- Neutron Scattering Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - B L Winn
- Neutron Scattering Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| |
Collapse
|
3
|
Scheie A, Laurell P, McClarty PA, Granroth GE, Stone MB, Moessner R, Nagler SE. Dirac Magnons, Nodal Lines, and Nodal Plane in Elemental Gadolinium. Phys Rev Lett 2022; 128:097201. [PMID: 35302826 DOI: 10.1103/physrevlett.128.097201] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 01/12/2022] [Indexed: 06/14/2023]
Abstract
We investigate the magnetic excitations of elemental gadolinium (Gd) using inelastic neutron scattering, showing that Gd is a Dirac magnon material with nodal lines at K and nodal planes at half integer ℓ. We find an anisotropic intensity winding around the K-point Dirac magnon cone, which is interpreted to indicate Berry phase physics. Using linear spin wave theory calculations, we show the nodal lines have nontrivial Berry phases, and topological surface modes. We also discuss the origin of the nodal plane in terms of a screw-axis symmetry, and introduce a topological invariant characterizing its presence and effect on the scattering intensity. Together, these results indicate a highly nontrivial topology, which is generic to hexagonal close packed ferromagnets. We discuss potential implications for other such systems.
Collapse
Affiliation(s)
- A Scheie
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Pontus Laurell
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - P A McClarty
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Str. 38, 01187 Dresden, Germany
| | - G E Granroth
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M B Stone
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - R Moessner
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Str. 38, 01187 Dresden, Germany
| | - S E Nagler
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Quantum Science Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| |
Collapse
|
4
|
Bai X, Paddison JAM, Kapit E, Koohpayeh SM, Wen JJ, Dutton SE, Savici AT, Kolesnikov AI, Granroth GE, Broholm CL, Chalker JT, Mourigal M. Magnetic Excitations of the Classical Spin Liquid MgCr_{2}O_{4}. Phys Rev Lett 2019; 122:097201. [PMID: 30932548 DOI: 10.1103/physrevlett.122.097201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Indexed: 06/09/2023]
Abstract
We report a comprehensive inelastic neutron-scattering study of the frustrated pyrochlore antiferromagnet MgCr_{2}O_{4} in its cooperative paramagnetic regime. Theoretical modeling yields a microscopic Heisenberg model with exchange interactions up to third-nearest neighbors, which quantitatively explains all of the details of the dynamic magnetic response. Our work demonstrates that the magnetic excitations in paramagnetic MgCr_{2}O_{4} are faithfully represented in the entire Brillouin zone by a theory of magnons propagating in a highly correlated paramagnetic background. Our results also suggest that MgCr_{2}O_{4} is proximate to a spiral spin-liquid phase distinct from the Coulomb phase, which has implications for the magnetostructural phase transition in MgCr_{2}O_{4}.
Collapse
Affiliation(s)
- X Bai
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - J A M Paddison
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
- Churchill College, University of Cambridge, Storey's Way, Cambridge CB3 0DS, United Kingdom
| | - E Kapit
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Parks Road, Oxford OX1 3NP, United Kingdom
- Department of Physics, Colorado School of Mines, Golden, Colorado 80401, USA
| | - S M Koohpayeh
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - J-J Wen
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - S E Dutton
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - A T Savici
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - A I Kolesnikov
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - G E Granroth
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - C L Broholm
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J T Chalker
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Parks Road, Oxford OX1 3NP, United Kingdom
| | - M Mourigal
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| |
Collapse
|
5
|
Banerjee A, Bridges CA, Yan JQ, Aczel AA, Li L, Stone MB, Granroth GE, Lumsden MD, Yiu Y, Knolle J, Bhattacharjee S, Kovrizhin DL, Moessner R, Tennant DA, Mandrus DG, Nagler SE. Proximate Kitaev quantum spin liquid behaviour in a honeycomb magnet. Nat Mater 2016; 15:733-740. [PMID: 27043779 DOI: 10.1038/nmat4604] [Citation(s) in RCA: 199] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 02/22/2016] [Indexed: 06/05/2023]
Abstract
Quantum spin liquids (QSLs) are topological states of matter exhibiting remarkable properties such as the capacity to protect quantum information from decoherence. Whereas their featureless ground states have precluded their straightforward experimental identification, excited states are more revealing and particularly interesting owing to the emergence of fundamentally new excitations such as Majorana fermions. Ideal probes of these excitations are inelastic neutron scattering experiments. These we report here for a ruthenium-based material, α-RuCl3, continuing a major search (so far concentrated on iridium materials) for realizations of the celebrated Kitaev honeycomb topological QSL. Our measurements confirm the requisite strong spin-orbit coupling and low-temperature magnetic order matching predictions proximate to the QSL. We find stacking faults, inherent to the highly two-dimensional nature of the material, resolve an outstanding puzzle. Crucially, dynamical response measurements above interlayer energy scales are naturally accounted for in terms of deconfinement physics expected for QSLs. Comparing these with recent dynamical calculations involving gauge flux excitations and Majorana fermions of the pure Kitaev model, we propose the excitation spectrum of α-RuCl3 as a prime candidate for fractionalized Kitaev physics.
Collapse
Affiliation(s)
- A Banerjee
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - C A Bridges
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - J-Q Yan
- Material Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - A A Aczel
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - L Li
- Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - M B Stone
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - G E Granroth
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
- Neutron Data Analysis &Visualization Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - M D Lumsden
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - Y Yiu
- Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - J Knolle
- Department of Physics, Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - S Bhattacharjee
- Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
- International Center for Theoretical Sciences, TIFR, Bangalore 560012, India
| | - D L Kovrizhin
- Department of Physics, Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - R Moessner
- Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
| | - D A Tennant
- Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - D G Mandrus
- Material Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - S E Nagler
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
- Bredesen Center, University of Tennessee, Knoxville, Tennessee 37966, USA
| |
Collapse
|
6
|
Fuhrman WT, Leiner J, Nikolić P, Granroth GE, Stone MB, Lumsden MD, DeBeer-Schmitt L, Alekseev PA, Mignot JM, Koohpayeh SM, Cottingham P, Phelan WA, Schoop L, McQueen TM, Broholm C. Interaction driven subgap spin exciton in the Kondo insulator SmB6. Phys Rev Lett 2015; 114:036401. [PMID: 25659009 DOI: 10.1103/physrevlett.114.036401] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Indexed: 06/04/2023]
Abstract
Using inelastic neutron scattering, we map a 14 meV coherent resonant mode in the topological Kondo insulator SmB6 and describe its relation to the low energy insulating band structure. The resonant intensity is confined to the X and R high symmetry points, repeating outside the first Brillouin zone and dispersing less than 2 meV, with a 5d-like magnetic form factor. We present a slave-boson treatment of the Anderson Hamiltonian with a third neighbor dominated hybridized band structure. This approach produces a spin exciton below the charge gap with features that are consistent with the observed neutron scattering. We find that maxima in the wave vector dependence of the inelastic neutron scattering indicate band inversion.
Collapse
Affiliation(s)
- W T Fuhrman
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - J Leiner
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - P Nikolić
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA and School of Physics, Astronomy and Computational Sciences, George Mason University, Fairfax, Virginia 22030, USA
| | - G E Granroth
- Neutron Data Analysis and Visualization Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M B Stone
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M D Lumsden
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - L DeBeer-Schmitt
- Instrument Source Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - P A Alekseev
- National Research Centre "Kurchatov Institute," 123182 Moscow, Russia and National Research Nuclear University "MEPhI," 115409 Moscow, Russia
| | - J-M Mignot
- Laboratoire Léon Brillouin, CEA-CNRS, CEA/Saclay, 91191 Gif sur Yvette, France
| | - S M Koohpayeh
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - P Cottingham
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA and Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - W Adam Phelan
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA and Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - L Schoop
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA and Department of Chemistry, Princeton University, Princeton, New Jersey 08540, USA
| | - T M McQueen
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA and Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA and Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - C Broholm
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA and Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA and Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| |
Collapse
|
7
|
Stone MB, Niedziela JL, Abernathy DL, DeBeer-Schmitt L, Ehlers G, Garlea O, Granroth GE, Graves-Brook M, Kolesnikov AI, Podlesnyak A, Winn B. A comparison of four direct geometry time-of-flight spectrometers at the Spallation Neutron Source. Rev Sci Instrum 2014; 85:045113. [PMID: 24784665 DOI: 10.1063/1.4870050] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The Spallation Neutron Source at Oak Ridge National Laboratory now hosts four direct geometry time-of-flight chopper spectrometers. These instruments cover a range of wave-vector and energy transfer space with varying degrees of neutron flux and resolution. The regions of reciprocal and energy space available to measure at these instruments are not exclusive and overlap significantly. We present a direct comparison of the capabilities of this instrumentation, conducted by data mining the instrument usage histories, and specific scanning regimes. In addition, one of the common science missions for these instruments is the study of magnetic excitations in condensed matter systems. We have measured the powder averaged spin wave spectra in one particular sample using each of these instruments, and use these data in our comparisons.
Collapse
Affiliation(s)
- M B Stone
- Quantum Condensed Matter Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J L Niedziela
- Instrument and Source Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - D L Abernathy
- Quantum Condensed Matter Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - L DeBeer-Schmitt
- Instrument and Source Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - G Ehlers
- Quantum Condensed Matter Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - O Garlea
- Quantum Condensed Matter Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - G E Granroth
- Neutron Data Analysis and Visualization Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M Graves-Brook
- Instrument and Source Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - A I Kolesnikov
- Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - A Podlesnyak
- Quantum Condensed Matter Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - B Winn
- Quantum Condensed Matter Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| |
Collapse
|
8
|
Aczel AA, Granroth GE, Macdougall GJ, Buyers WJL, Abernathy DL, Samolyuk GD, Stocks GM, Nagler SE. Quantum oscillations of nitrogen atoms in uranium nitride. Nat Commun 2012; 3:1124. [PMID: 23047682 DOI: 10.1038/ncomms2117] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 09/04/2012] [Indexed: 11/09/2022] Open
Abstract
The vibrational excitations of crystalline solids corresponding to acoustic or optic one-phonon modes appear as sharp features in measurements such as neutron spectroscopy. In contrast, many-phonon excitations generally produce a complicated, weak and featureless response. Here we present time-of-flight neutron scattering measurements for the binary solid uranium nitride, showing well-defined, equally spaced, high-energy vibrational modes in addition to the usual phonons. The spectrum is that of a single atom, isotropic quantum harmonic oscillator and characterizes independent motions of light nitrogen atoms, each found in an octahedral cage of heavy uranium atoms. This is an unexpected and beautiful experimental realization of one of the fundamental, exactly solvable problems in quantum mechanics. There are also practical implications, as the oscillator modes must be accounted for in the design of generation IV nuclear reactors that plan to use uranium nitride as a fuel.
Collapse
Affiliation(s)
- A A Aczel
- Quantum Condensed Matter Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Nojiri H, Yoshii S, Yasui M, Okada K, Matsuda M, Jung JS, Kimura T, Santodonato L, Granroth GE, Ross KA, Carlo JP, Gaulin BD. Neutron Laue diffraction study on the magnetic phase diagram of multiferroic MnWO4 under pulsed high magnetic fields. Phys Rev Lett 2011; 106:237202. [PMID: 21770542 DOI: 10.1103/physrevlett.106.237202] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Indexed: 05/31/2023]
Abstract
We have combined time-of-flight neutron Laue diffraction and pulsed high magnetic fields at the Spallation Neutron Source to study the phase diagram of the multiferroic material MnWO(4). The control of the field-pulse timing enabled an exploration of magnetic Bragg scattering through the time dependence of both the neutron wavelength and the pulsed magnetic field. This allowed us to observe several magnetic Bragg peaks in different field-induced phases of MnWO(4) with a single instrument configuration. These phases were not previously amenable to neutron diffraction studies due to the large fields involved.
Collapse
Affiliation(s)
- H Nojiri
- Institute for Materials Research, Tohoku University, Sendai, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Clancy JP, Gaulin BD, Adams CP, Granroth GE, Kolesnikov AI, Sherline TE, Chou FC. Singlet-triplet excitations in the unconventional spin-Peierls TiOBr compound. Phys Rev Lett 2011; 106:117401. [PMID: 21469893 DOI: 10.1103/physrevlett.106.117401] [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: 09/21/2010] [Indexed: 05/30/2023]
Abstract
We have performed time-of-flight neutron scattering measurements on powder samples of the unconventional spin-Peierls compound TiOBr using the fine-resolution Fermi chopper spectrometer (SEQUOIA) at the Spallation Neutron Source at Oak Ridge National Laboratory. These measurements reveal two branches of magnetic excitations within the commensurate and incommensurate spin-Peierls phases, which we associate with n=1 and n=2 triplet excitations out of the singlet ground state. These results represent the first direct measurement of the singlet-triplet energy gap in TiOBr, which has a value of E(g)=21.2±1.0 meV.
Collapse
Affiliation(s)
- J P Clancy
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1, Canada
| | | | | | | | | | | | | |
Collapse
|
11
|
Granroth GE, Kolesnikov AI, Sherline TE, Clancy JP, Ross KA, Ruff JPC, Gaulin BD, Nagler SE. SEQUOIA: A Newly Operating Chopper Spectrometer at the SNS. ACTA ACUST UNITED AC 2010. [DOI: 10.1088/1742-6596/251/1/012058] [Citation(s) in RCA: 162] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
12
|
Stone MB, Tian W, Lumsden MD, Granroth GE, Mandrus D, Chung JH, Harrison N, Nagler SE. Quantum spin correlations in an organometallic alternating-sign chain. Phys Rev Lett 2007; 99:087204. [PMID: 17930978 DOI: 10.1103/physrevlett.99.087204] [Citation(s) in RCA: 2] [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: 05/03/2007] [Indexed: 05/25/2023]
Abstract
High resolution neutron scattering is used to study excitations in the organometallic magnet (CH3)2NH2CuCl3 (DMACuCl3). Combined with bulk magnetization and susceptibility studies, the new results imply that DMACuCl3 is a realization of the S=1/2 alternating antiferromagnetic-ferromagnetic (AFM-FM) chain. Coupled-cluster calculations indicate that the AFM and FM interactions have nearly the same strength, while analysis of scattering intensities shows evidence for interdimer spin correlations. Results are discussed in the context of recent ideas concerning quantum entanglement.
Collapse
Affiliation(s)
- M B Stone
- Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Watson BC, Kotov VN, Meisel MW, Hall DW, Granroth GE, Montfrooij WT, Nagler SE, Jensen DA, Backov R, Petruska MA, Fanucci GE, Talham DR. Magnetic spin ladder (C5H12N)2CuBr4: high-field magnetization and scaling near quantum criticality. Phys Rev Lett 2001; 86:5168-5171. [PMID: 11384448 DOI: 10.1103/physrevlett.86.5168] [Citation(s) in RCA: 30] [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] [Received: 08/09/2000] [Indexed: 05/23/2023]
Abstract
The magnetization, M(H< or =30 T,0.7< or =T< or =300 K), of (C5H12N)2CuBr4 has been used to identify this system as an S = 1/2 Heisenberg two-leg ladder in the strong-coupling limit, J( perpendicular) = 13.3 K and J( parallel) = 3.8 K, with H(c1) = 6.6 T and H(c2) = 14.6 T. An inflection point in M(H,T = 0.7 K) at half saturation, M(s)/2, is described by an effective XXZ chain. The data exhibit universal scaling behavior in the vicinity of H(c1) and H(c2), indicating that the system is near a quantum critical point.
Collapse
Affiliation(s)
- B C Watson
- Department of Physics and The Center for Condensed Matter Sciences, University of Florida, P.O. Box 118440, Gainesville, Florida 32611-8440, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Granroth GE, Meisel MW, Chaparala M, Jolicoeur T, Ward BH, Talham DR. Experimental Evidence of a Haldane Gap in an S=2 Quasi-Linear-Chain Antiferromagnet. Phys Rev Lett 1996; 77:1616-1619. [PMID: 10063123 DOI: 10.1103/physrevlett.77.1616] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
|