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Das S, Dey D, Raghunathan R, Soos ZG, Kumar M, Ramasesha S. Quantum phase transitions in skewed ladder systems. Phys Chem Chem Phys 2023; 26:36-46. [PMID: 38086628 DOI: 10.1039/d3cp04179d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
In this brief review, we introduce a new spin ladder system called skewed spin ladders and discuss the exotic quantum phases of this system. The spin ladders studied are the 5/7, 3/4 and 3/5 systems corresponding to alternately fused 5 and 7 membered rings; 3 and 4 membered rings; and 3 and 5 membered rings. These ladders show completely different behaviour as the Hamiltonian model parameter is changed. When the Hamiltonian parameter is increased the 5/7 ladder switches from an initial singlet ground state to progressively higher spin ground state and then to a reentrant singlet state before finally settling to the highest spin ground state whose spin equals the number of unit cells in the system. The 3/4 ladder goes from a singlet ground state to a high spin ground state with each unit cell contributing spin 1 to the state, as the model parameter is increased. The 3/5 ladder shows a singlet ground state for small parameters and high spin ground state for intermediate values of the parameter and for still higher parameters, a reentrant singlet ground state. They can also show interesting magnetization plateaus as illustrated by studies on a specific spin ladder.
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Affiliation(s)
- Sambunath Das
- Institute of Physics (FZU), Czech Academy of Sciences, Na Slovance 1999/2, 182 00 Prague, Czech Republic
| | - Dayasindhu Dey
- UGC-DAE Consortium for Scientific Research, Indore-452001, Madhya Pradesh, India
| | - Rajamani Raghunathan
- UGC-DAE Consortium for Scientific Research, Indore-452001, Madhya Pradesh, India
| | - Zoltan G Soos
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Manoranjan Kumar
- S. N. Bose National Centre for Basic Sciences, Block - JD, Sector - III, Salt Lake, Kolkata-700106, India.
| | - S Ramasesha
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru 560012, India.
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2
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Tseng Y, Paris E, Schmidt KP, Zhang W, Asmara TC, Bag R, Strocov VN, Singh S, Schlappa J, Rønnow HM, Schmitt T. Momentum-resolved spin-conserving two-triplon bound state and continuum in a cuprate ladder. COMMUNICATIONS PHYSICS 2023; 6:138. [PMID: 38665396 PMCID: PMC11041747 DOI: 10.1038/s42005-023-01250-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 05/23/2023] [Indexed: 04/28/2024]
Abstract
Studying multi-particle elementary excitations has provided unique access to understand collective many-body phenomena in correlated electronic materials, paving the way towards constructing microscopic models. In this work, we perform O K-edge resonant inelastic X-ray scattering (RIXS) on the quasi-one-dimensional cuprate Sr 14 Cu 24 O 41 with weakly-doped spin ladders. The RIXS signal is dominated by a dispersing sharp mode ~ 270 meV on top of a damped incoherent component ~ 400-500 meV. Comparing with model calculations using the perturbative continuous unitary transformations method, the two components resemble the spin-conserving ΔS = 0 two-triplon bound state and continuum excitations in the spin ladders. Such multi-spin response with long-lived ΔS = 0 excitons is central to several exotic magnetic properties featuring Majorana fermions, yet remains unexplored given the generally weak cross-section with other experimental techniques. By investigating a simple spin-ladder model system, our study provides valuable insight into low-dimensional quantum magnetism.
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Affiliation(s)
- Yi Tseng
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
- Laboratory for Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Present Address: Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Eugenio Paris
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Kai P. Schmidt
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstraße 7, D-91058 Erlangen, Germany
| | - Wenliang Zhang
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Teguh Citra Asmara
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Rabindranath Bag
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra 411008 India
- Present Address: Department of Physics, Duke University, Durham, NC 27708 USA
| | - Vladimir N. Strocov
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Surjeet Singh
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra 411008 India
| | - Justine Schlappa
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
- European X-Ray Free-Electron Laser Facility GmbH, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Henrik M. Rønnow
- Laboratory for Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Thorsten Schmitt
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
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3
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Mühlhauser M, Schmidt KP. Linked cluster expansions via hypergraph decompositions. Phys Rev E 2022; 105:064110. [PMID: 35854571 DOI: 10.1103/physreve.105.064110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
We propose a hypergraph expansion which facilitates the direct treatment of quantum spin models with many-site interactions via perturbative linked cluster expansions. The main idea is to generate all relevant subclusters and sort them into equivalence classes essentially governed by hypergraph isomorphism. Concretely, a reduced König representation of the hypergraphs is used to make the equivalence relation accessible by graph isomorphism. During this procedure we determine the embedding factor for each equivalence class, which is used in the final resummation in order to obtain the final result. As an instructive example we calculate the ground-state energy and a particular excitation gap of the plaquette Ising model in a transverse field on the three-dimensional cubic lattice.
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Affiliation(s)
- Matthias Mühlhauser
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstrasse 7, D-91058 Erlangen, Germany
| | - Kai Phillip Schmidt
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstrasse 7, D-91058 Erlangen, Germany
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Terakado N, Nara Y, Machida Y, Takahashi Y, Fujiwara T. Dynamic control of heat flow using a spin-chain ladder cuprate film and an ionic liquid. Sci Rep 2020; 10:14468. [PMID: 32879343 PMCID: PMC7468102 DOI: 10.1038/s41598-020-70835-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 08/03/2020] [Indexed: 11/09/2022] Open
Abstract
Dynamic control of heat flow for applications in thermal management has attracted much interest in fields such as electronics and thermal engineering. Spin-chain ladder cuprates are promising materials to realize dynamic control of heat flow, since their magnon thermal conductivity is sensitive to the hole density in the spin ladders, which can be dynamically controlled by an external field. Here, we demonstrate the electric control of heat flow using a polycrystalline cuprate film and an ionic liquid. The results showed that a voltage application to the interface causes imperfectly recoverable decreases in both the thermal conductance of the film and the peak due to magnons in the Raman spectra. This result may be attributed to an increase in the hole density in the spin ladders. This report highlights that magnon thermal conduction has potential for the development of advanced thermal management applications.
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Affiliation(s)
- Nobuaki Terakado
- Department of Applied Physics, Tohoku University, 6-6-05 Aoba, Aoba-ku, Sendai, 980-8579, Japan. .,JST, PRESTO, 4-1-8 Honcho, Kawaguchi, 332-0012, Japan.
| | - Yoshinori Nara
- Department of Applied Physics, Tohoku University, 6-6-05 Aoba, Aoba-ku, Sendai, 980-8579, Japan
| | - Yuki Machida
- Department of Applied Physics, Tohoku University, 6-6-05 Aoba, Aoba-ku, Sendai, 980-8579, Japan
| | - Yoshihiro Takahashi
- Department of Applied Physics, Tohoku University, 6-6-05 Aoba, Aoba-ku, Sendai, 980-8579, Japan
| | - Takumi Fujiwara
- Department of Applied Physics, Tohoku University, 6-6-05 Aoba, Aoba-ku, Sendai, 980-8579, Japan.
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Hörmann M, Wunderlich P, Schmidt KP. Dynamic Structure Factor of Disordered Quantum Spin Ladders. PHYSICAL REVIEW LETTERS 2018; 121:167201. [PMID: 30387667 DOI: 10.1103/physrevlett.121.167201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Indexed: 06/08/2023]
Abstract
We investigate the impact of quenched disorder on the zero-temperature dynamic structure factor of two-leg quantum spin ladders. Using linked-cluster expansions and bond-operator mean-field theory, huge effects on individual quasiparticles but also on composite bound states and two-quasiparticle continua are observed. This leads to intriguing quantum structures in dynamical correlation functions well observable in spectroscopic experiments.
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Affiliation(s)
- Max Hörmann
- Institute for Theoretical Physics, FAU Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Paul Wunderlich
- Institute for Theoretical Physics, FAU Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - K P Schmidt
- Institute for Theoretical Physics, FAU Erlangen-Nürnberg, 91058 Erlangen, Germany
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Ward S, Mena M, Bouillot P, Kollath C, Giamarchi T, Schmidt KP, Normand B, Krämer KW, Biner D, Bewley R, Guidi T, Boehm M, McMorrow DF, Rüegg C. Bound States and Field-Polarized Haldane Modes in a Quantum Spin Ladder. PHYSICAL REVIEW LETTERS 2017; 118:177202. [PMID: 28498681 DOI: 10.1103/physrevlett.118.177202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Indexed: 06/07/2023]
Abstract
The challenge of one-dimensional systems is to understand their physics beyond the level of known elementary excitations. By high-resolution neutron spectroscopy in a quantum spin-ladder material, we probe the leading multiparticle excitation by characterizing the two-magnon bound state at zero field. By applying high magnetic fields, we create and select the singlet (longitudinal) and triplet (transverse) excitations of the fully spin-polarized ladder, which have not been observed previously and are close analogs of the modes anticipated in a polarized Haldane chain. Theoretical modeling of the dynamical response demonstrates our complete quantitative understanding of these states.
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Affiliation(s)
- S Ward
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
- Department of Quantum Matter Physics, University of Geneva, CH-1211 Geneva, Switzerland
| | - M Mena
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
- Department of Quantum Matter Physics, University of Geneva, CH-1211 Geneva, Switzerland
| | - P Bouillot
- Department of Medical Imaging and Information Sciences, Interventional Neuroradiology Unit, University Hospitals of Geneva, CH-1211 Geneva, Switzerland
- Laboratory for Hydraulic Machines, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - C Kollath
- Department of Quantum Matter Physics, University of Geneva, CH-1211 Geneva, Switzerland
- HISKP, University of Bonn, Nussallee 14-16, 53115 Bonn, Germany
| | - T Giamarchi
- Department of Quantum Matter Physics, University of Geneva, CH-1211 Geneva, Switzerland
| | - K P Schmidt
- Theoretische Physik I, Staudtstrasse 7, FAU Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - B Normand
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - K W Krämer
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland
| | - D Biner
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland
| | - R Bewley
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxford OX11 0QX, United Kingdom
| | - T Guidi
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxford OX11 0QX, United Kingdom
| | - M Boehm
- Institut Laue Langevin, 6 rue Jules Horowitz BP156, 38024 Grenoble CEDEX 9, France
| | - D F McMorrow
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Ch Rüegg
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Department of Quantum Matter Physics, University of Geneva, CH-1211 Geneva, Switzerland
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Montagnese M, Otter M, Zotos X, Fishman DA, Hlubek N, Mityashkin O, Hess C, Saint-Martin R, Singh S, Revcolevschi A, van Loosdrecht PHM. Phonon-magnon interaction in low dimensional quantum magnets observed by dynamic heat transport measurements. PHYSICAL REVIEW LETTERS 2013; 110:147206. [PMID: 25167033 DOI: 10.1103/physrevlett.110.147206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Indexed: 06/03/2023]
Abstract
Thirty-five years ago, Sanders and Walton [Phys. Rev. B 15, 1489 (1977)] proposed a method to measure the phonon-magnon interaction in antiferromagnets through thermal transport which so far has not been verified experimentally. We show that a dynamical variant of this approach allows direct extraction of the phonon-magnon equilibration time, yielding 400 μs for the cuprate spin-ladder system Ca(9)La(5)Cu(24)O(41). The present work provides a general method to directly address the spin-phonon interaction by means of dynamical transport experiments.
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Affiliation(s)
- Matteo Montagnese
- Zernike Institute for Advanced Materials, Rijksuniversiteit Groningen, Nijenborgh 4, 9747 AG, The Netherlands
| | - Marian Otter
- Zernike Institute for Advanced Materials, Rijksuniversiteit Groningen, Nijenborgh 4, 9747 AG, The Netherlands
| | - Xenophon Zotos
- Department of Physics, University of Crete and Foundation for Research and Technology-Hellas, 71003 Heraklion, Greece
| | - Dmitry A Fishman
- Zernike Institute for Advanced Materials, Rijksuniversiteit Groningen, Nijenborgh 4, 9747 AG, The Netherlands
| | - Nikolai Hlubek
- IFW-Dresden, Institute for Solid State Research, P.O. Box 270116, D-01171 Dresden, Germany
| | - Oleg Mityashkin
- IFW-Dresden, Institute for Solid State Research, P.O. Box 270116, D-01171 Dresden, Germany
| | - Christian Hess
- IFW-Dresden, Institute for Solid State Research, P.O. Box 270116, D-01171 Dresden, Germany
| | - Romuald Saint-Martin
- Laboratoire de Physico-Chimie de L'Etat Solide, ICMMO, UMR8182, Université Paris-Sud, 91405 Orsay CEDEX, France
| | - Surjeet Singh
- Laboratoire de Physico-Chimie de L'Etat Solide, ICMMO, UMR8182, Université Paris-Sud, 91405 Orsay CEDEX, France
| | - Alexandre Revcolevschi
- Laboratoire de Physico-Chimie de L'Etat Solide, ICMMO, UMR8182, Université Paris-Sud, 91405 Orsay CEDEX, France
| | - Paul H M van Loosdrecht
- Zernike Institute for Advanced Materials, Rijksuniversiteit Groningen, Nijenborgh 4, 9747 AG, The Netherlands
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Choi KY, Hwang JW, Lemmens P, Wulferding D, Shu GJ, Chou FC. Evidence for dimer crystal melting in the frustrated spin-ladder system BiCu2PO6. PHYSICAL REVIEW LETTERS 2013; 110:117204. [PMID: 25166571 DOI: 10.1103/physrevlett.110.117204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 01/19/2013] [Indexed: 06/03/2023]
Abstract
In the spin ladder compound BiCu(2)PO(6), there exists a decisive dynamics of spin excitations that we classify and characterize using inelastic light scattering. We observe an interladder singlet bound mode at 24 cm(-1) and two intraladder bound states at 62 and 108 cm(-1) in the leg (bb) and the rung (cc) polarization as well as a broad triplon continuum extending from 36 cm(-1) to 700 cm(-1). Though isolated spin ladder physics can roughly account for the observed excitations at high energies, frustration and interladder interactions need to be considered to fully describe the spectral distribution and scattering selection rules at low and intermediate energies. In addition, we attribute the rich spectrum of singlet bound modes to a melting of a dimer crystal. Our study provides evidence for a Z(2) quantum phase transition from a dimer to a resonating valence bond state driven by singlet fluctuations.
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Affiliation(s)
- K-Y Choi
- Department of Physics, Chung-Ang University, 221 Huksuk-Dong, Seoul 156-756, Republic of Korea
| | - J W Hwang
- Department of Physics, Chung-Ang University, 221 Huksuk-Dong, Seoul 156-756, Republic of Korea
| | - P Lemmens
- Institute for Condensed Matter Physics, TU Braunschweig, D-38106 Braunschweig, Germany
| | - D Wulferding
- Institute for Condensed Matter Physics, TU Braunschweig, D-38106 Braunschweig, Germany
| | - G J Shu
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - F C Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
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Ding LJ, Yao KL, Fu HH. Field-controlled Luttinger liquid and possible crossover into spin liquid in strong-rail ladder systems. Chemphyschem 2010; 11:3291-8. [PMID: 20839268 DOI: 10.1002/cphc.201000410] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The thermodynamics and transport properties of strong-rail ladder systems are investigated by means of Green's function theory. It is shown that the magnetic behavior clearly manifests a typical antiferromagnetism with gapped or gapless low-lying excitations, which is in agreement with the experimental results. In addition, the temperature-field-induced phase diagram is explored, and we demonstrate a Luttinger liquid behavior in the window h(c) (marking the ending of the M=0 plateau)<h<h(s) (saturation magnetic field) within a narrow range of temperature. The spin liquid phase is uncovered for h<h(c) upon cooling down to zero temperature. It is also shown that the rung entanglement entropy is a good indicator for detecting the field-driven quantum criticality. Meanwhile, the magnetic susceptibility, the specific heat, and the thermal (spin) Drude weights are calculated to characterize the plentiful quantum phases, in which the thermal insulating and conducting behaviors can be controlled by magnetic fields.
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Affiliation(s)
- Lin-Jie Ding
- School of Physics and Wuhan High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
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Schlappa J, Schmitt T, Vernay F, Strocov VN, Ilakovac V, Thielemann B, Rønnow HM, Vanishri S, Piazzalunga A, Wang X, Braicovich L, Ghiringhelli G, Marin C, Mesot J, Delley B, Patthey L. Collective magnetic excitations in the spin ladder Sr14Cu24O41 measured using high-resolution resonant inelastic x-ray scattering. PHYSICAL REVIEW LETTERS 2009; 103:047401. [PMID: 19659397 DOI: 10.1103/physrevlett.103.047401] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Indexed: 05/28/2023]
Abstract
We investigate magnetic excitations in the spin-ladder compound Sr_{14}Cu_{24}O_{41} using high-resolution Cu L_{3} edge resonant inelastic x-ray scattering (RIXS). Our findings demonstrate that RIXS couples to two-triplon collective excitations. In contrast to inelastic neutron scattering, the RIXS cross section changes only moderately over the entire Brillouin zone, revealing high sensitivity also at small momentum transfers, allowing determination of the two-triplon energy gap as 100 +/- 30 meV. Our results are backed by calculations within an effective Hubbard model for a finite-size cluster, and confirm that optical selection rules are obeyed for excitations from this spherically symmetric quantum spin-liquid ground state.
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Affiliation(s)
- J Schlappa
- Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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Notbohm S, Ribeiro P, Lake B, Tennant DA, Schmidt KP, Uhrig GS, Hess C, Klingeler R, Behr G, Büchner B, Reehuis M, Bewley RI, Frost CD, Manuel P, Eccleston RS. One- and two-triplon spectra of a cuprate ladder. PHYSICAL REVIEW LETTERS 2007; 98:027403. [PMID: 17358648 DOI: 10.1103/physrevlett.98.027403] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Indexed: 05/14/2023]
Abstract
We have performed inelastic neutron scattering on the near ideal spin-ladder compound La4Sr10Cu24O41 as a starting point for investigating doped ladders and their tendency toward superconductivity. A key feature was the separation of one-triplon and two-triplon scattering. Two-triplon scattering is observed quantitatively for the first time and so access is realized to the important strong magnetic quantum fluctuations. The spin gap is found to be 26.4+/-0.3 meV. The data are successfully modeled using the continuous unitary transformation method, and the exchange constants are determined by fitting to be Jleg=186 meV and Jrung=124 meV along the leg and rung, respectively; a substantial cyclic exchange of Jcyc=31 meV is confirmed.
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Affiliation(s)
- S Notbohm
- Hahn-Meitner-Institut Berlin, Berlin, Germany
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13
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Schmidt KP, Uhrig GS. Excitations in one-dimensional S = 1/2 quantum antiferromagnets. PHYSICAL REVIEW LETTERS 2003; 90:227204. [PMID: 12857339 DOI: 10.1103/physrevlett.90.227204] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2002] [Indexed: 05/24/2023]
Abstract
The transition from dimerized to uniform phases is studied in terms of spectral weights for spin chains using continuous unitary transformations. The spectral weights in the S=1 channel are computed perturbatively around the limit of strong dimerization. We find that the spectral weight is concentrated mainly in the subspaces with a small number of elementary triplets (triplons), even for vanishing dimerization. So, besides spinons, triplons may be used as elementary excitations in spin chains. We conclude that there is no necessity to use fractional excitations in low-dimensional, undoped, or doped quantum antiferromagnets.
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Affiliation(s)
- Kai P Schmidt
- Institut für Theoretische Physik, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln, Germany
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14
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Alvarez JV, Gros C. Anomalous thermal conductivity of frustrated heisenberg spin chains and ladders. PHYSICAL REVIEW LETTERS 2002; 89:156603. [PMID: 12366009 DOI: 10.1103/physrevlett.89.156603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2002] [Revised: 09/09/2002] [Indexed: 05/23/2023]
Abstract
We study the thermal transport properties of several quantum-spin chains and ladders. We find indications for a diverging thermal conductivity at finite temperatures for the models examined. The temperature at which the nondiverging prefactor kappa((th))(T) peaks is, in general, substantially lower than the temperature at which the corresponding specific heat c(V)(T) is maximal. We show that this result of the microscopic approach leads to a substantial reduction for estimates of the magnetic mean-free path lambda extracted by analyzing recent experiments, as compared to similar analyses by phenomenological theories.
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Affiliation(s)
- J V Alvarez
- Fakultät 7, Theoretische Physik, University of the Saarland, 66041 Saarbrücken, Germany
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15
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Knetter C, Schmidt KP, Grüninger M, Uhrig GS. Fractional and integer excitations in quantum antiferromagnetic spin 1/2 ladders. PHYSICAL REVIEW LETTERS 2001; 87:167204. [PMID: 11690239 DOI: 10.1103/physrevlett.87.167204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2001] [Indexed: 05/23/2023]
Abstract
Spectral densities are computed in unprecedented detail for quantum antiferromagnetic spin 1/2 two-leg ladders. These results were obtained due to a major methodical advance achieved by optimally chosen unitary transformations. The approach is based on dressed integer excitations. Considerable weight is found at high energies in the two-particle sector. Precursors of fractional spinon physics occur supporting the conclusion that there is no necessity to resort to fractional excitations in order to describe features at higher energies.
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Affiliation(s)
- C Knetter
- Institut für Theoretische Physik, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln, Germany
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