1
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Songvilay M, Petit S, Damay F, Roux G, Qureshi N, Walker HC, Rodriguez-Rivera JA, Gao B, Cheong SW, Stock C. From One- to Two-Magnon Excitations in the S=3/2 Magnet β-CaCr_{2}O_{4}. Phys Rev Lett 2021; 126:017201. [PMID: 33480800 DOI: 10.1103/physrevlett.126.017201] [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: 06/02/2020] [Revised: 10/14/2020] [Accepted: 12/07/2020] [Indexed: 06/12/2023]
Abstract
We apply neutron spectroscopy to measure the magnetic dynamics in the S=3/2 magnet β-CaCr_{2}O_{4} (T_{N}=21 K). The low-energy fluctuations, in the ordered state, resemble large-S linear spin waves from the incommensurate ground state. However, at higher energy transfers, these semiclassical and harmonic dynamics are replaced by an energy and momentum broadened continuum of excitations. Applying kinematic constraints required for energy and momentum conservation, sum rules of neutron scattering, and comparison against exact diagonalization calculations, we show that the dynamics at high-energy transfers resemble low-S one-dimensional quantum fluctuations. β-CaCr_{2}O_{4} represents an example of a magnet at the border between classical Néel and quantum phases, displaying dual characteristics.
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Affiliation(s)
- M Songvilay
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
| | - S Petit
- Laboratoire Léon Brillouin, CEA-CNRS UMR 12, 91191 Gif-Sur-Yvette Cedex, France
| | - F Damay
- Laboratoire Léon Brillouin, CEA-CNRS UMR 12, 91191 Gif-Sur-Yvette Cedex, France
| | - G Roux
- Université Paris-Saclay, CNRS, LPTMS, 91405 Orsay, France
| | - N Qureshi
- Institut Laue-Langevin, 6 rue Jules Horowitz, Boite postale 156, 38042 Grenoble, France
| | - H C Walker
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, United Kingdom
| | - J A Rodriguez-Rivera
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
- Department of Materials Science, University of Maryland, College Park, Maryland 20742, USA
| | - B Gao
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
| | - S-W Cheong
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
| | - C Stock
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
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2
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Zhang J, Phelan D, Botana AS, Chen YS, Zheng H, Krogstad M, Wang SG, Qiu Y, Rodriguez-Rivera JA, Osborn R, Rosenkranz S, Norman MR, Mitchell JF. Intertwined density waves in a metallic nickelate. Nat Commun 2020; 11:6003. [PMID: 33243978 PMCID: PMC7691989 DOI: 10.1038/s41467-020-19836-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [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: 07/24/2020] [Accepted: 11/03/2020] [Indexed: 11/09/2022] Open
Abstract
Nickelates are a rich class of materials, ranging from insulating magnets to superconductors. But for stoichiometric materials, insulating behavior is the norm, as for most late transition metal oxides. Notable exceptions are the 3D perovskite LaNiO3, an unconventional paramagnetic metal, and the layered Ruddlesden-Popper phases R4Ni3O10, (R = La, Pr, Nd). The latter are particularly intriguing because they exhibit an unusual metal-to-metal transition. Here, we demonstrate that this transition results from an incommensurate density wave with both charge and magnetic character that lies closer in its behavior to the metallic density wave seen in chromium metal than the insulating stripes typically found in single-layer nickelates like La2-xSrxNiO4. We identify these intertwined density waves as being Fermi surface-driven, revealing a novel ordering mechanism in this nickelate that reflects a coupling among charge, spin, and lattice degrees of freedom that differs not only from the single-layer materials, but from the 3D perovskites as well. Layered Ruddlesden-Popper structure nickelates R4Ni3O10 (R = La,Pr) show an unusual metal-to-metal transition, but its origin has remained elusive for more than two decades. Here, the authors show that this transition results from intertwined density waves that arise from a coupling between charge and spin degrees of freedom
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Affiliation(s)
- Junjie Zhang
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, United States. .,Institute of Crystal Materials, State Key Laboratory of Crystal Materials, Shandong University, 250100, Jinan, Shandong, China.
| | - D Phelan
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, United States
| | - A S Botana
- Department of Physics, Arizona State University, Tempe, AZ, 85287, United States
| | - Yu-Sheng Chen
- ChemMatCARS, The University of Chicago, Lemont, IL, 60439, United States
| | - Hong Zheng
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, United States
| | - M Krogstad
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, United States
| | - Suyin Grass Wang
- ChemMatCARS, The University of Chicago, Lemont, IL, 60439, United States
| | - Yiming Qiu
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, United States
| | - J A Rodriguez-Rivera
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, United States.,Department of Materials Science, University of Maryland, College Park, MD, 20742, United States
| | - R Osborn
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, United States
| | - S Rosenkranz
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, United States
| | - M R Norman
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, United States
| | - J F Mitchell
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, United States.
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3
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Luo Y, Marcus GG, Trump BA, Kindervater J, Stone MB, Rodriguez-Rivera JA, Qiu Y, McQueen TM, Tchernyshyov O, Broholm C. Low-energy magnons in the chiral ferrimagnet Cu 2OSeO 3: A coarse-grained approach. Phys Rev B 2020; 101:10.1103/PhysRevB.101.144411. [PMID: 33655091 PMCID: PMC7919739 DOI: 10.1103/physrevb.101.144411] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We report a comprehensive neutron scattering study of low energy magnetic excitations in the breathing pyrochlore helimagnetic Cu2OSeO3. Fully documenting the four lowest energy magnetic modes that leave the ferrimagnetic configuration of the "strong tetrahedra" intact ( | ℏ ω | < 13 meV), we find gapless quadratic dispersion at the point for energies above 0.2 meV, two doublets separated by 1.6(2) meV at the R point, and a bounded continuum at the X point. Our constrained rigid spin cluster model relates these features to Dzyaloshinskii-Moriya (DM) interactions and the incommensurate helical ground state. Combining conventional spin wave theory with a spin cluster form factor accurately reproduces the measured equal time structure factor through multiple Brillouin zones. An effective spin Hamiltonian describing complex anisotropic intercluster interactions is obtained.
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Affiliation(s)
- Yi Luo
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - G. G. Marcus
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - B. A. Trump
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA
| | - J. Kindervater
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - M. B. Stone
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J. A. Rodriguez-Rivera
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - Yiming Qiu
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA
| | - T. M. McQueen
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - O. Tchernyshyov
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - C. Broholm
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
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4
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Kim MG, Winn B, Chi S, Savici AT, Rodriguez-Rivera JA, Chen WC, Xu X, Li Y, Kim JW, Cheong SW, Kiryukhin V. Spin-liquid-like state in pure and Mn-doped TbInO 3 with a nearly triangular lattice. Phys Rev B 2019; 100:10.1103/PhysRevB.100.024405. [PMID: 38712019 PMCID: PMC11071068 DOI: 10.1103/physrevb.100.024405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Inelastic neutron scattering studies in single crystals of TbInO3 and TbIn0.95Mn0.05O3 with nearly triangular antiferromagnetic lattice are reported. At low energies, a broad and apparently gapless continuum of magnetic excitations, located at the triangular lattice (TL) Brillouin zone boundary, is observed. The data are well described by the uncorrelated nearest-neighbor valence bonds model. At higher energies, a broad excitation branch dispersing from the TL zone boundary is observed. No signs of static magnetic order are found down to the temperatures two orders of magnitude smaller than the effective interaction energy. The fluctuating magnetic moment exceeds two-thirds of the Tb3+ free-ion value and is confined to the TL plane. These observations are consistent with a TL-based spin liquid state in TbInO3.
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Affiliation(s)
- M G Kim
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - B Winn
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - S Chi
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - A T Savici
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J A Rodriguez-Rivera
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
- Department of Materials Science, University of Maryland, College Park, Maryland 20742, USA
| | - W C Chen
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
- Department of Materials Science, University of Maryland, College Park, Maryland 20742, USA
| | - X Xu
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Y Li
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - J W Kim
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - S-W Cheong
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - V Kiryukhin
- Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
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5
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Songvilay M, Rodriguez EE, Lindsay R, Green MA, Walker HC, Rodriguez-Rivera JA, Stock C. Anharmonic Magnon Excitations in Noncollinear and Charge-Ordered RbFe^{2+}Fe^{3+}F_{6}. Phys Rev Lett 2018; 121:087201. [PMID: 30192563 DOI: 10.1103/physrevlett.121.087201] [Citation(s) in RCA: 1] [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: 01/17/2018] [Revised: 05/10/2018] [Indexed: 06/08/2023]
Abstract
RbFe^{2+}Fe^{3+}F_{6} is an example of a charge ordered antiferromagnet where iron sites, with differing valences, are structurally separated into two interpenetrating sublattices. The low temperature magnetically ordered Fe^{2+} (S=2) and Fe^{3+} (S=5/2) moments form a noncollinear orthogonal structure with the Fe^{3+} site displaying a reduced static ordered moment. Neutron spectroscopy on single crystals finds two distinct spin wave branches with a dominant coupling along the Fe^{3+} chain axis (b axis). High resolution spectroscopic measurements find an intense energy and momentum broadened magnetic band of scattering bracketing a momentum-energy region where two magnon processes are kinematically allowed. These anharmonic excitations are enhanced in this noncollinear magnet owing to the orthogonal spin arrangement.
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Affiliation(s)
- M Songvilay
- School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
| | - E E Rodriguez
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
| | - R Lindsay
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - M A Green
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - H C Walker
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, United Kingdom
| | - J A Rodriguez-Rivera
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
- Department of Materials Science, University of Maryland, College Park, Maryland 20742, USA
| | - C Stock
- School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
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6
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Stock C, Rodriguez-Rivera JA, Schmalzl K, Demmel F, Singh DK, Ronning F, Thompson JD, Bauer ED. From Ising Resonant Fluctuations to Static Uniaxial Order in Antiferromagnetic and Weakly Superconducting CeCo(In_{1-x}Hg_{x})_{5}(x=0.01). Phys Rev Lett 2018; 121:037003. [PMID: 30085774 DOI: 10.1103/physrevlett.121.037003] [Citation(s) in RCA: 1] [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: 02/01/2018] [Indexed: 06/08/2023]
Abstract
CeCo(In_{0.990}Hg_{0.010})_{5} is a charge doped variant of the d-wave CoCoIn_{5} superconductor with coexistent antiferromagnetic and superconducting transitions occurring at T_{N}=3.4 and T_{c}=1.4 K, respectively. We use neutron diffraction and spectroscopy to show that the magnetic resonant fluctuations present in the parent superconducting phase are replaced by collinear c-axis magnetic order with three-dimensional Ising critical fluctuations. No low-energy transverse spin fluctuations are observable in this doping-induced antiferromagnetic phase and the dynamic resonant spectral weight predominately shifts to the elastic channel. Static (τ>0.2 ns) collinear Ising order is proximate to superconductivity in CeCoIn_{5} and is stabilized through hole doping with Hg.
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Affiliation(s)
- C Stock
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
| | - J A Rodriguez-Rivera
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
- Department of Materials Science, University of Maryland, College Park, Maryland 20742, USA
| | - K Schmalzl
- Forschungszentrum Juelich GmbH, Juelich Centre for Neutron Science at ILL, 71 avenue des Martyrs, 38000 Grenoble, France
| | - F Demmel
- ISIS Facility, Rutherford Appleton Labs, Chilton, Didcot OX11 0QX, United Kingdom
| | - D K Singh
- Department of Physics and Astronomy, University of Missouri, Missouri 65211, USA
| | - F Ronning
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J D Thompson
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - E D Bauer
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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7
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Fuhrman WT, Chamorro JR, Alekseev PA, Mignot JM, Keller T, Rodriguez-Rivera JA, Qiu Y, Nikolić P, McQueen TM, Broholm CL. Screened moments and extrinsic in-gap states in samarium hexaboride. Nat Commun 2018; 9:1539. [PMID: 29670117 PMCID: PMC5906653 DOI: 10.1038/s41467-018-04007-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [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: 07/12/2017] [Accepted: 03/27/2018] [Indexed: 11/20/2022] Open
Abstract
Samarium hexaboride (SmB6) is a Kondo insulator, with a narrow gap due to hybridization between localized and conduction electrons. Despite being an insulator, many samples show metal-like properties. Rare-earth purification is exceedingly difficult, and nominally pure samples may contain 2% or more of impurities. Here to determine the effects of rare-earth doping on SmB6, we synthesized and probed a series of gadolinium-doped samples. We found a relationship between specific heat and impurity moment screening which scales systematically. Consistent with this finding, our neutron scattering experiments of a high purity sample of doubly isotopic 154Sm11B6 show no intrinsic excitations below the well-established 13 meV spin-exciton. The result of introducing impurities into a Kondo insulator is incompletely understood, but it is clear from our measurements that there is a systematic relationship between rare-earth impurities and metal-like properties in SmB6. The unconventional behaviour of samarium hexaboride has been difficult to explain in part because of differences between samples. Here the authors use gadolinium to exemplify that hard to avoid impurities introduce a low energy density of states that may explain earlier observations.
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Affiliation(s)
- W T Fuhrman
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, 21218, USA.
| | - J R Chamorro
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Chemistry, The Johns Hopkins University, Baltimore, MD, 21218, USA
| | - P A Alekseev
- National Research Centre "Kurchatov Institute", 123182, Moscow, Russia.,National Research Nuclear University "MEPhI", 115409, Moscow, Russia
| | - J-M Mignot
- Laboratoire Léon Brillouin, CEA-CNRS, CEA/Saclay, 91191, Gif sur Yvette, France
| | - T Keller
- Max Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569, Stuttgart, Germany.,Max Planck Society at the Forschungsneutronenquelle Heinz Maier-Leibnitz (MLZ), D-85747, Garching, Germany
| | - J A Rodriguez-Rivera
- Department of Materials Sciences, University of Maryland, College Park, MD, 20742, USA.,NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Y Qiu
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - P Nikolić
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, 21218, USA.,School of Physics, Astronomy and Computational Sciences, George Mason University, Fairfax, VA, 22030, USA
| | - T M McQueen
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Chemistry, The Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, MD, 21218, USA
| | - C L Broholm
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, MD, 21218, USA
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8
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Stock C, Rodriguez EE, Lee N, Demmel F, Fouquet P, Laver M, Niedermayer C, Su Y, Nemkovski K, Green MA, Rodriguez-Rivera JA, Kim JW, Zhang L, Cheong SW. Orphan Spins in the S=5/2 Antiferromagnet CaFe_{2}O_{4}. Phys Rev Lett 2017; 119:257204. [PMID: 29303328 DOI: 10.1103/physrevlett.119.257204] [Citation(s) in RCA: 2] [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: 05/12/2017] [Indexed: 06/07/2023]
Abstract
CaFe_{2}O_{4} is an anisotropic S=5/2 antiferromagnet with two competing A (↑↑↓↓) and B (↑↓↑↓) magnetic order parameters separated by static antiphase boundaries at low temperatures. Neutron diffraction and bulk susceptibility measurements, show that the spins near these boundaries are weakly correlated and a carry an uncompensated ferromagnetic moment that can be tuned with a magnetic field. Spectroscopic measurements find these spins are bound with excitation energies less than the bulk magnetic spin waves and resemble the spectra from isolated spin clusters. Localized bound orphaned spins separate the two competing magnetic order parameters in CaFe_{2}O_{4}.
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Affiliation(s)
- C Stock
- School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
| | - E E Rodriguez
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
| | - N Lee
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
| | - F Demmel
- ISIS Facility, Rutherford Appleton Labs, Chilton, Didcot OX11 0QX, United Kingdom
| | - P Fouquet
- Institute Laue-Langevin, 6 rue Jules Horowitz, Boite Postale 156, 38042 Grenoble Cedex 9, France
| | - M Laver
- School of Metallurgy and Materials, University of Birmingham, B15 2TT, United Kingdom
| | - Ch Niedermayer
- Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - Y Su
- Jülich Centre for Neuton Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, D-85747 Garching, Germany
| | - K Nemkovski
- Jülich Centre for Neuton Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, D-85747 Garching, Germany
| | - M A Green
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - J A Rodriguez-Rivera
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
- Department of Materials Science, University of Maryland, College Park, Maryland 20742, USA
| | - J W Kim
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
| | - L Zhang
- Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - S-W Cheong
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
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9
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Stock C, Rodriguez EE, Lee N, Green MA, Demmel F, Ewings RA, Fouquet P, Laver M, Niedermayer C, Su Y, Nemkovski K, Rodriguez-Rivera JA, Cheong SW. Solitary Magnons in the S=5/2 Antiferromagnet CaFe_{2}O_{4}. Phys Rev Lett 2016; 117:017201. [PMID: 27419585 DOI: 10.1103/physrevlett.117.017201] [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] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Indexed: 06/06/2023]
Abstract
CaFe_{2}O_{4} is a S=5/2 anisotropic antiferromagnet based upon zig-zag chains having two competing magnetic structures, denoted as the A (↑↑↓↓) and B (↑↓↑↓) phases, which differ by the c-axis stacking of ferromagnetic stripes. We apply neutron scattering to demonstrate that the competing A and B phase order parameters result in magnetic antiphase boundaries along c which freeze on the time scale of ∼1 ns at the onset of magnetic order at 200 K. Using high resolution neutron spectroscopy, we find quantized spin wave levels and measure 9 such excitations localized in regions ∼1-2 c-axis lattice constants in size. We discuss these in the context of solitary magnons predicted to exist in anisotropic systems. The magnetic anisotropy affords both competing A+B orders as well as localization of spin excitations in a classical magnet.
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Affiliation(s)
- C Stock
- School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
| | - E E Rodriguez
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
| | - N Lee
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
| | - M A Green
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - F Demmel
- ISIS Facility, Rutherford Appleton Labs, Chilton, Didcot OX11 0QX, United Kingdom
| | - R A Ewings
- ISIS Facility, Rutherford Appleton Labs, Chilton, Didcot OX11 0QX, United Kingdom
| | - P Fouquet
- Institute Laue-Langevin, 6 rue Jules Horowitz, Boite Postale 156, 38042 Grenoble Cedex 9, France
| | - M Laver
- School of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Ch Niedermayer
- Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - Y Su
- Jülich Centre for Neuton Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, D-85747 Garching, Germany
| | - K Nemkovski
- Jülich Centre for Neuton Science JCNS, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, D-85747 Garching, Germany
| | - J A Rodriguez-Rivera
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
- Department of Materials Science, University of Maryland, College Park, Maryland 20742, USA
| | - S-W Cheong
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
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10
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Wang CH, Poudel L, Taylor AE, Lawrence JM, Christianson AD, Chang S, Rodriguez-Rivera JA, Lynn JW, Podlesnyak AA, Ehlers G, Baumbach RE, Bauer ED, Gofryk K, Ronning F, McClellan KJ, Thompson JD. Quantum critical fluctuations in the heavy fermion compound Ce(Ni0.935Pd0.065)₂Ge₂. J Phys Condens Matter 2015; 27:015602. [PMID: 25469766 DOI: 10.1088/0953-8984/27/1/015602] [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] [Indexed: 06/04/2023]
Abstract
Electric resistivity, specific heat, magnetic susceptibility, and inelastic neutron scattering experiments were performed on a single crystal of the heavy fermion compound Ce(Ni0.935Pd0.065)2Ge2 in order to study the spin fluctuations near an antiferromagnetic (AF) quantum critical point (QCP). The resistivity and the specific heat coefficient for T ⩽ 1 K exhibit the power law behavior expected for a 3D itinerant AF QCP (ρ(T) ∼ T(3/2) and γ(T) ∼ γ0 - bT(1/2)). However, for 2 ⩽ T ⩽ 10 K, the susceptibility and specific heat vary as log T and the resistivity varies linearly with temperature. Furthermore, despite the fact that the resistivity and specific heat exhibit the non-Fermi liquid behavior expected at a QCP, the correlation length, correlation time, and staggered susceptibility of the spin fluctuations remain finite at low temperature. We suggest that these deviations from the divergent behavior expected for a QCP may result from alloy disorder.
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Affiliation(s)
- C H Wang
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. University of California, Irvine, CA 92697, USA
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Mourigal M, Fuhrman WT, Sheckelton JP, Wartelle A, Rodriguez-Rivera JA, Abernathy DL, McQueen TM, Broholm CL. Molecular quantum magnetism in LiZn2Mo3O8. Phys Rev Lett 2014; 112:027202. [PMID: 24484043 DOI: 10.1103/physrevlett.112.027202] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Indexed: 06/03/2023]
Abstract
Inelastic neutron scattering at low temperatures T≤30 K from a powder of LiZn2Mo3O8 demonstrates this triangular-lattice antiferromagnet hosts collective magnetic excitations from spin-1/2 Mo3O13 molecules. Apparently gapless (Δ<0.2 meV) and extending at least up to 2.5 meV, the low-energy magnetic scattering cross section is surprisingly broad in momentum space and involves one-third of the spins present above 100 K. The data are compatible with the presence of valence bonds involving nearest-neighbor and next-nearest-neighbor spins forming a disordered or dynamic state.
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Affiliation(s)
- M Mourigal
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - W T Fuhrman
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - J P Sheckelton
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - A Wartelle
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA and École Normale Supérieure de Lyon, Université de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
| | - J A Rodriguez-Rivera
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA and Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - D L Abernathy
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6475, USA
| | - T M McQueen
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - C L Broholm
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA and NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA and Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6475, USA
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Nakatsuji S, Kuga K, Kimura K, Satake R, Katayama N, Nishibori E, Sawa H, Ishii R, Hagiwara M, Bridges F, Ito TU, Higemoto W, Karaki Y, Halim M, Nugroho AA, Rodriguez-Rivera JA, Green MA, Broholm C. Spin-Orbital Short-Range Order on a Honeycomb-Based Lattice. Science 2012; 336:559-63. [DOI: 10.1126/science.1212154] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Thampy V, Kang J, Rodriguez-Rivera JA, Bao W, Savici AT, Hu J, Liu TJ, Qian B, Fobes D, Mao ZQ, Fu CB, Chen WC, Ye Q, Erwin RW, Gentile TR, Tesanovic Z, Broholm C. Friedel-like oscillations from interstitial iron in superconducting Fe(1+y)Te0.62Se0.38. Phys Rev Lett 2012; 108:107002. [PMID: 22463442 DOI: 10.1103/physrevlett.108.107002] [Citation(s) in RCA: 7] [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: 09/23/2011] [Indexed: 05/31/2023]
Abstract
Using polarized and unpolarized neutron scattering, we show that interstitial Fe in superconducting Fe(1+y)Te(1-x)Se(x) induces a magnetic Friedel-like oscillation that diffracts at Q⊥=(1/2 0) and involves >50 neighboring Fe sites. The interstitial >2μ(B) moment is surrounded by compensating ferromagnetic four-spin clusters that may seed double stripe ordering in Fe(1+y)Te. A semimetallic five-band model with (1/2 1/2) Fermi surface nesting and fourfold symmetric superexchange between interstitial Fe and two in-plane nearest neighbors largely accounts for the observed diffraction.
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Affiliation(s)
- V Thampy
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
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Cao H, Gehring PM, Devreugd CP, Rodriguez-Rivera JA, Li J, Viehland D. Role of nanoscale precipitates on the enhanced magnetostriction of heat-treated galfenol (Fe1-xGax) alloys. Phys Rev Lett 2009; 102:127201. [PMID: 19392316 DOI: 10.1103/physrevlett.102.127201] [Citation(s) in RCA: 7] [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: 05/10/2008] [Revised: 12/22/2008] [Indexed: 05/27/2023]
Abstract
We report neutron diffuse scattering measurements on highly magnetostrictive Fe1-xGax alloys (0.14<x<0.20) with different thermal treatments. This diffuse scattering scales with magnetostriction and exhibits asymmetric peaks at the (100) and (300) reciprocal lattice positions that are consistent with the coexistence of short-range ordered, coherent nanometer-scale precipitates embedded in a long-range ordered, body-centered cubic matrix. A large peak splitting is observed at (300) for x=0.19, which indicates that the nanoprecipitates are not cubic and have a large elastic strain. This implies a structural origin for the enhanced magnetostriction.
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Affiliation(s)
- H Cao
- Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061, USA
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