1
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Jażdżewska A, Mierzejewski M, Środa M, Nocera A, Alvarez G, Dagotto E, Herbrych J. Transition to the Haldane phase driven by electron-electron correlations. Nat Commun 2023; 14:8524. [PMID: 38129389 PMCID: PMC10740019 DOI: 10.1038/s41467-023-44135-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 12/01/2023] [Indexed: 12/23/2023] Open
Abstract
One of the most famous quantum systems with topological properties, the spin [Formula: see text] antiferromagnetic Heisenberg chain, is well-known to display exotic [Formula: see text] edge states. However, this spin model has not been analyzed from the more general perspective of strongly correlated systems varying the electron-electron interaction strength. Here, we report the investigation of the emergence of the Haldane edge in a system of interacting electrons - the two-orbital Hubbard model-with increasing repulsion strength U and Hund interaction JH. We show that interactions not only form the magnetic moments but also form a topologically nontrivial fermionic many-body ground-state with zero-energy edge states. Specifically, upon increasing the strength of the Hubbard repulsion and Hund exchange, we identify a sharp transition point separating topologically trivial and nontrivial ground-states. Surprisingly, such a behaviour appears already at rather small values of the interaction, in a regime where the magnetic moments are barely developed.
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Affiliation(s)
- A Jażdżewska
- Faculty of Physics and Astronomy, University of Wrocław, 50-383, Wrocław, Poland
| | - M Mierzejewski
- Institute of Theoretical Physics, Wrocław University of Science and Technology, 50-370, Wrocław, Poland
| | - M Środa
- Institute of Theoretical Physics, Wrocław University of Science and Technology, 50-370, Wrocław, Poland
| | - A Nocera
- Department of Physics and Astronomy and Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
| | - G Alvarez
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - E Dagotto
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - J Herbrych
- Institute of Theoretical Physics, Wrocław University of Science and Technology, 50-370, Wrocław, Poland.
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2
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Galeski S, Povarov KY, Blosser D, Gvasaliya S, Wawrzynczak R, Ollivier J, Gooth J, Zheludev A. LT Scaling in Depleted Quantum Spin Ladders. PHYSICAL REVIEW LETTERS 2022; 128:237201. [PMID: 35749184 DOI: 10.1103/physrevlett.128.237201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 05/02/2022] [Accepted: 05/10/2022] [Indexed: 06/15/2023]
Abstract
Using a combination of neutron scattering, calorimetry, quantum Monte Carlo simulations, and analytic results we uncover confinement effects in depleted, partially magnetized quantum spin ladders. We show that introducing nonmagnetic impurities into magnetized spin ladders leads to the emergence of a new characteristic length L in the otherwise scale-free Tomonaga-Luttinger liquid (serving as the effective low-energy model). This results in universal LT scaling of staggered susceptibilities. Comparison of simulation results with experimental phase diagrams of prototypical spin ladder compounds bis(2,3-dimethylpyridinium)tetrabromocuprate(II) (DIMPY) and bis(piperidinium)tetrabromocuprate(II) (BPCB) yields excellent agreement.
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Affiliation(s)
- S Galeski
- Laboratory for Solid State Physics, ETH Zürich, 8093 Zürich, Switzerland
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40,01187 Dresden, Germany
| | - K Yu Povarov
- Laboratory for Solid State Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - D Blosser
- Laboratory for Solid State Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - S Gvasaliya
- Laboratory for Solid State Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - R Wawrzynczak
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40,01187 Dresden, Germany
- Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble, France
| | - J Ollivier
- Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble, France
| | - J Gooth
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40,01187 Dresden, Germany
| | - A Zheludev
- Laboratory for Solid State Physics, ETH Zürich, 8093 Zürich, Switzerland
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3
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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}. PHYSICAL REVIEW LETTERS 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] [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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4
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Sibille R, Lhotel E, Ciomaga Hatnean M, Nilsen GJ, Ehlers G, Cervellino A, Ressouche E, Frontzek M, Zaharko O, Pomjakushin V, Stuhr U, Walker HC, Adroja DT, Luetkens H, Baines C, Amato A, Balakrishnan G, Fennell T, Kenzelmann M. Coulomb spin liquid in anion-disordered pyrochlore Tb 2Hf 2O 7. Nat Commun 2017; 8:892. [PMID: 29026077 PMCID: PMC5638941 DOI: 10.1038/s41467-017-00905-w] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 08/03/2017] [Indexed: 11/14/2022] Open
Abstract
The charge ordered structure of ions and vacancies characterizing rare-earth pyrochlore oxides serves as a model for the study of geometrically frustrated magnetism. The organization of magnetic ions into networks of corner-sharing tetrahedra gives rise to highly correlated magnetic phases with strong fluctuations, including spin liquids and spin ices. It is an open question how these ground states governed by local rules are affected by disorder. Here we demonstrate in the pyrochlore Tb2Hf2O7, that the vicinity of the disordering transition towards a defective fluorite structure translates into a tunable density of anion Frenkel disorder while cations remain ordered. Quenched random crystal fields and disordered exchange interactions can therefore be introduced into otherwise perfect pyrochlore lattices of magnetic ions. We show that disorder can play a crucial role in preventing long-range magnetic order at low temperatures, and instead induces a strongly fluctuating Coulomb spin liquid with defect-induced frozen magnetic degrees of freedom. Experimental studies of frustrated spin systems such as pyrochlore magnetic oxides test our understanding of quantum many-body physics. Here the authors show experimentally that Tb2Hf2O7 may be a model material for investigating how structural disorder can stabilize a quantum spin liquid phase.
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Affiliation(s)
- Romain Sibille
- Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland. .,Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland.
| | - Elsa Lhotel
- Institut Néel, CNRS-Université Grenoble Alpes, 38042, Grenoble, France
| | | | - Gøran J Nilsen
- Institut Laue-Langevin, CS 20156, 38042, Grenoble, France.,ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX, UK
| | - Georg Ehlers
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Antonio Cervellino
- Swiss Light Source, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - Eric Ressouche
- Université Grenoble Alpes, CEA INAC, MEM, 38000, Grenoble, France
| | - Matthias Frontzek
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland.,Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Oksana Zaharko
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - Vladimir Pomjakushin
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - Uwe Stuhr
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - Helen C Walker
- ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX, UK
| | - Devashibhai T Adroja
- ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX, UK
| | - Hubertus Luetkens
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - Chris Baines
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - Alex Amato
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | | | - Tom Fennell
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - Michel Kenzelmann
- Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland.,Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
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5
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Yue XY, Ouyang ZW, Sun YC, Xia ZC, Rao GH. Size reduction-induced chain breaking in Haldane-chain compounds SrNi 2-x Mg x V 2O 8 (x = 0 and 0.1). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:245802. [PMID: 28452742 DOI: 10.1088/1361-648x/aa7039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report size reduction-induced chain breaking in the spin-1 Haldane-chain SrNi2-x Mg x V2O8 (x = 0 and 0.1) by magnetization and electron spin resonance measurements. For x = 0.0, the magnetic susceptibility of all samples can be well described by a temperature-independent term, a Curie-Weiss term and a Haldane-gap term. This implies that a reduced sample grain size breaks the long chain and creates a considerable number of S = 1/2 edge spins, resulting in the enhancement of magnetization and the decrease of Haldane gap in the samples. These edge spins as well as the other paramagnetic ions at grain boundary and surface might be weakly coupled with each other. For the Mg-doped sample with x = 0.1, there are more S = 1/2 spins creased in relative to x = 0.0 because of a combined effect of lattice defects, Mg-doping and reduced size. In addition, the antiferromagnetic resonance of x = 0.1 is also presented.
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Affiliation(s)
- X Y Yue
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China. School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
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6
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Dupont M, Capponi S, Laflorencie N. Disorder-Induced Revival of the Bose-Einstein Condensation in Ni(Cl_{1-x}Br_{x})_{2}-4SC(NH_{2})_{2} at High Magnetic Fields. PHYSICAL REVIEW LETTERS 2017; 118:067204. [PMID: 28234502 DOI: 10.1103/physrevlett.118.067204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Indexed: 06/06/2023]
Abstract
Building on recent NMR experiments [A. Orlova et al., Phys. Rev. Lett. 118, 067203 (2017).PRLTAO0031-900710.1103/PhysRevLett.118.067203], we theoretically investigate the high magnetic field regime of the disordered quasi-one-dimensional S=1 antiferromagnetic material Ni(Cl_{1-x}Br_{x})_{2}-4SC(NH_{2})_{2}. The interplay between disorder, chemically controlled by Br-doping, interactions, and the external magnetic field, leads to a very rich phase diagram. Beyond the well-known antiferromagnetically ordered regime, an analog of a Bose condensate of magnons, which disappears when H≥12.3 T, we unveil a resurgence of phase coherence at a higher field H∼13.6 T, induced by the doping. Interchain couplings stabilize the finite temperature long-range order whose extension in the field-temperature space is governed by the concentration of impurities x. Such a "minicondensation" contrasts with previously reported Bose-glass physics in the same regime and should be accessible to experiments.
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Affiliation(s)
- Maxime Dupont
- Laboratoire de Physique Théorique, IRSAMC, Université de Toulouse, CNRS, 31062 Toulouse, France
| | - Sylvain Capponi
- Laboratoire de Physique Théorique, IRSAMC, Université de Toulouse, CNRS, 31062 Toulouse, France
| | - Nicolas Laflorencie
- Laboratoire de Physique Théorique, IRSAMC, Université de Toulouse, CNRS, 31062 Toulouse, France
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7
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Schmidiger D, Povarov KY, Galeski S, Reynolds N, Bewley R, Guidi T, Ollivier J, Zheludev A. Emergent Interacting Spin Islands in a Depleted Strong-Leg Heisenberg Ladder. PHYSICAL REVIEW LETTERS 2016; 116:257203. [PMID: 27391748 DOI: 10.1103/physrevlett.116.257203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Indexed: 06/06/2023]
Abstract
Properties of the depleted Heisenberg spin ladder material series (C_{7}H_{10}N)_{2}Cu_{1-z}Zn_{z}Br_{4} have been studied by the combination of magnetic measurements and neutron spectroscopy. Disorder-induced degrees of freedom lead to a specific magnetic response, described in terms of emergent strongly interacting "spin island" objects. The structure and dynamics of the spin islands is studied by high-resolution inelastic neutron scattering. This allows us to determine their spatial shape and to observe their mutual interactions, manifested by strong spectral in-gap contributions.
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Affiliation(s)
- D Schmidiger
- Neutron Scattering and Magnetism, Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - K Yu Povarov
- Neutron Scattering and Magnetism, Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - S Galeski
- Neutron Scattering and Magnetism, Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - N Reynolds
- Neutron Scattering and Magnetism, Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - R Bewley
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, United Kingdom
| | - T Guidi
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, United Kingdom
| | - J Ollivier
- Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble, France
| | - A Zheludev
- Neutron Scattering and Magnetism, Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
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8
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Direct observation of finite size effects in chains of antiferromagnetically coupled spins. Nat Commun 2015; 6:7061. [PMID: 25952539 PMCID: PMC4432630 DOI: 10.1038/ncomms8061] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 03/26/2015] [Indexed: 11/14/2022] Open
Abstract
Finite spin chains made of few magnetic ions are the ultimate-size structures that can be engineered to perform spin manipulations for quantum information devices. Their spin structure is expected to show finite size effects and its knowledge is of great importance both for fundamental physics and applications. Until now a direct and quantitative measurement of the spatial distribution of the magnetization of such small structures has not been achieved even with the most advanced microscopic techniques. Here we present measurements of the spin density distribution of a finite chain of eight spin-3/2 ions using polarized neutron diffraction. The data reveal edge effects that are a consequence of the finite size and of the parity of the chain and indicate a noncollinear spin arrangement. This is in contrast with the uniform spin distribution observed in the parent closed chain and the collinear arrangement in odd-open chains. Molecular magnets are among the smallest structures that may be exploited for quantum information processing. Here, Guidi et al. use polarized neutron scattering to observe finite size effects and a noncollinear spin arrangement in a Cr8Cd ring molecule, an even-numbered open antiferromagnetic spin-3/2 chain.
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9
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Stock C, Broholm C, Demmel F, Van Duijn J, Taylor JW, Kang HJ, Hu R, Petrovic C. From incommensurate correlations to mesoscopic spin resonance in YbRh2Si2. PHYSICAL REVIEW LETTERS 2012; 109:127201. [PMID: 23005978 DOI: 10.1103/physrevlett.109.127201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Indexed: 06/01/2023]
Abstract
Spin fluctuations are reported near the magnetic field-driven quantum critical point in YbRh(2)Si(2). On cooling, ferromagnetic fluctuations evolve into incommensurate correlations located at q(0) = ±(δ,δ), with δ = 0.14 ± 0.04 r.l.u. At low temperatures, an in-plane magnetic field induces a sharp intradoublet resonant excitation at an energy E(0) = gμ(B)μ(0)H with g = 3.8 ± 0.2. The intensity is localized at the zone center, indicating precession of spin density extending ξ = 6 ± 2 Å beyond the 4f site.
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Affiliation(s)
- C Stock
- NIST Center for Neutron Research, Gaithersburg, Maryland 20899, USA
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10
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Cheng JG, Li G, Balicas L, Zhou JS, Goodenough JB, Xu C, Zhou HD. High-pressure sequence of Ba3NiSb2O9 structural phases: new S = 1 quantum spin liquids based on Ni2+. PHYSICAL REVIEW LETTERS 2011; 107:197204. [PMID: 22181641 DOI: 10.1103/physrevlett.107.197204] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Indexed: 05/31/2023]
Abstract
Two new gapless quantum spin-liquid candidates with S = 1 (Ni(2+)) moments: the 6H-B phase of Ba(3)NiSb(2)O(9) with a Ni(2+)-triangular lattice and the 3C phase with a Ni(2/3)Sb(1/3)-three-dimensional edge-shared tetrahedral lattice were obtained under high pressure. Both compounds show no magnetic order down to 0.35 K despite Curie-Weiss temperatures θ(CW) of -75.5 (6H-B) and -182.5 K (3C), respectively. Below ~25 K, the magnetic susceptibility of the 6H-B phase saturates to a constant value χ(0) = 0.013 emu/mol, which is followed below 7 K by a linear-temperature-dependent magnetic specific heat (C(M)) displaying a giant coefficient γ = 168 mJ/mol K(2). Both observations suggest the development of a Fermi-liquid-like ground state. For the 3C phase, the C(M) perpendicular T(2) behavior indicates a unique S = 1, 3D quantum spin-liquid ground state.
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Affiliation(s)
- J G Cheng
- Texas Materials Institute, University of Texas at Austin, Texas 78712, USA
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11
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Xu G, Broholm C, Soh YA, Aeppli G, Ditusa JF, Chen Y, Kenzelmann M, Frost CD, Ito T, Oka K, Takagi H. Mesoscopic Phase Coherence in a Quantum Spin Fluid. Science 2007; 317:1049-52. [PMID: 17656685 DOI: 10.1126/science.1143831] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Mesoscopic quantum phase coherence is important because it improves the prospects for handling quantum degrees of freedom in technology. Here we show that the development of such coherence can be monitored using magnetic neutron scattering from a one-dimensional spin chain of an oxide of nickel (Y2BaNiO5), a quantum spin fluid in which no classical static magnetic order is present. In the cleanest samples, the quantum coherence length is 20 nanometers, which is almost an order of magnitude larger than the classical antiferromagnetic correlation length of 3 nanometers. We also demonstrate that the coherence length can be modified by static and thermally activated defects in a quantitatively predictable manner.
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Affiliation(s)
- Guangyong Xu
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA.
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12
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Haravifard S, Dunsiger SR, El Shawish S, Gaulin BD, Dabkowska HA, Telling MTF, Perring TG, Bonca J. In-gap spin excitations and finite triplet lifetimes in the dilute singlet ground state system SrCu(2-x)Mgx(BO3)2. PHYSICAL REVIEW LETTERS 2006; 97:247206. [PMID: 17280317 DOI: 10.1103/physrevlett.97.247206] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Indexed: 05/13/2023]
Abstract
High resolution neutron scattering measurements on a single crystal of SrCu(2-x)Mgx(BO3)2 with x approximately 0.05 reveal the presence of new spin excitations within the gap of this quasi-two-dimensional, singlet ground state system. The application of a magnetic field induces Zeeman-split states associated with S=1/2 unpaired spins which are antiferromagnetically correlated with the bulk singlet. Substantial broadening of both the one- and two-triplet excitations in the doped single crystal is observed, as compared with pure SrCu2(BO3)2. Theoretical calculations using a variational algorithm and a single quenched magnetic vacancy on an infinite lattice are shown to qualitatively account for these effects.
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Affiliation(s)
- S Haravifard
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
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13
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Yoshida M, Shiraki K, Okubo S, Ohta H, Ito T, Takagi H, Kaburagi M, Ajiro Y. Energy structure of a finite Haldane chain in Y2BaNi0.96Mg0.04O5 studied by high field electron spin resonance. PHYSICAL REVIEW LETTERS 2005; 95:117202. [PMID: 16197040 DOI: 10.1103/physrevlett.95.117202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2005] [Indexed: 05/04/2023]
Abstract
This Letter presents the fine structure of energy levels for the edge states of a Haldane chain. In order to investigate the edge states, we have performed high field and multifrequency electron spin resonance (ESR) measurements of finite length S=1 antiferromagnetic chains in Y2BaNi0.96Mg0.04O5. Owing to the high spectral resolution by high fields and high frequencies, observed ESR signals can be separated into the contributions of the finite chains with various chain lengths. Our results clearly show that the edge spins actually interact with each other through the quantum spin chain and the interaction depends on the chain length N. This N dependence has been obtained experimentally for the first time, and shows that the correlation length xi in the real system is somewhat larger than that calculated by a simple Heisenberg model.
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Affiliation(s)
- M Yoshida
- Venture Business Laboratory, Kobe University, Kobe 657-8501, Japan
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14
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Lou J, Chen C, Zhao J, Wang X, Xiang T, Su Z, Yu L. Midgap states in antiferromagnetic Heisenberg chains with a staggered field. PHYSICAL REVIEW LETTERS 2005; 94:217207. [PMID: 16090347 DOI: 10.1103/physrevlett.94.217207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Indexed: 05/03/2023]
Abstract
We study low-energy excitations in antiferromagnetic Heisenberg chains with a staggered field which splits the spectrum into a longitudinal and a transverse branch. Bound states are found to exist inside the field induced gap in both branches. They originate from the edge effects and are inherent to spin-chain materials. The sine-Gordon scaling h(2/3)(s)[log(h(s)](1/6) (h(s), the staggered field) provides an accurate description for the gap and midgap energies in the transverse branch for S=1/2 and the midgap energies in both branches for S=3/2 over a wide range of magnetic field; however, it can fit other low-energy excitations only at much lower field. Moreover, the integer-spin S=1 chain displays scaling behavior that does not fit this scaling law. These results reveal intriguing features of magnetic excitations in spin-chain materials that deserve further investigation.
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Affiliation(s)
- Jizhong Lou
- Department of Physics, University of Nevada, Las Vegas, Nevada 89154, USA
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Lou J, Qin S, Chen C. String order in half-integer-spin antiferromagnetic Heisenberg chains. PHYSICAL REVIEW LETTERS 2003; 91:087204. [PMID: 14525273 DOI: 10.1103/physrevlett.91.087204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2003] [Indexed: 05/24/2023]
Abstract
We derive the extended string order parameter O(S) for antiferromagnetic Heisenberg chains with half-integer spin S in the valence-bond-solid picture. We obtain the analytic power-law scaling of O(S) versus the chain length L and show that O(S) scales at an extremely slow pace that decreases rapidly with growing spin magnitude. Furthermore, accurate numerical calculations show that the power-law scaling sets in only when L exceeds a characteristic length scale l(S) which increases very fast with growing S. Consequently, a pseudo-long-range string order exists in half-integer-spin Heisenberg chains. The implications of this result and its relationship to other topological features such as the end-chain states are discussed.
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Affiliation(s)
- Jizhong Lou
- Department of Physics, University of Nevada, Las Vegas, NV 89154, USA
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