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Huang Q, Rawl R, Xie WW, Chou ES, Zapf VS, Ding XX, Mauws C, Wiebe CR, Feng EX, Cao HB, Tian W, Ma J, Qiu Y, Butch N, Zhou HD. Non-magnetic ion site disorder effects on the quantum magnetism of a spin-1/2 equilateral triangular lattice antiferromagnet. J Phys Condens Matter 2022; 34:205401. [PMID: 35189602 DOI: 10.1088/1361-648x/ac5703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 02/21/2022] [Indexed: 06/14/2023]
Abstract
With the motivation to study how non-magnetic ion site disorder affects the quantum magnetism of Ba3CoSb2O9, a spin-1/2 equilateral triangular lattice antiferromagnet, we performed DC and AC susceptibility, specific heat, elastic and inelastic neutron scattering measurements on single crystalline samples of Ba2.87Sr0.13CoSb2O9with Sr doping on non-magnetic Ba2+ion sites. The results show that Ba2.87Sr0.13CoSb2O9exhibits (i) a two-step magnetic transition at 2.7 K and 3.3 K, respectively; (ii) a possible canted 120 degree spin structure at zero field with reduced ordered moment as 1.24μB/Co; (iii) a series of spin state transitions for bothH∥ab-plane andH∥c-axis. ForH∥ab-plane, the magnetization plateau feature related to the up-up-down phase is significantly suppressed; (iv) an inelastic neutron scattering spectrum with only one gapped mode at zero field, which splits to one gapless and one gapped mode at 9 T. All these features are distinctly different from those observed for the parent compound Ba3CoSb2O9, which demonstrates that the non-magnetic ion site disorder (the Sr doping) plays a complex role on the magnetic properties beyond the conventionally expected randomization of the exchange interactions. We propose the additional effects including the enhancement of quantum spin fluctuations and introduction of a possible spatial anisotropy through the local structural distortions.
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Affiliation(s)
- Q Huang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, United States of America
| | - R Rawl
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, United States of America
| | - W W Xie
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, United States of America
| | - E S Chou
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, United States of America
| | - V S Zapf
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, NM 87545, United States of America
| | - X X Ding
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, NM 87545, United States of America
| | - C Mauws
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - C R Wiebe
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
- Department of Chemistry, University of Winnipeg, Winnipeg, Manitoba R3B 2E9, Canada
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - E X Feng
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America
| | - H B Cao
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America
| | - W Tian
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America
| | - J Ma
- Laboratory of Artificial Structures and Quantum Control, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 110016 Shenyang, People's Republic of China
| | - Y Qiu
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States of America
| | - N Butch
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States of America
| | - H D Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, United States of America
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, United States of America
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Mauws C, Hiebert N, Rutherford ML, Zhou HD, Huang Q, Stone MB, Butch NP, Su Y, Choi ES, Yamani Z, Wiebe CR. Magnetic ordering in the Ising antiferromagnetic pyrochlore Nd 2ScNbO 7. J Phys Condens Matter 2021; 33:245802. [PMID: 33827056 DOI: 10.1088/1361-648x/abf594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/07/2021] [Indexed: 06/12/2023]
Abstract
The question of structural disorder and its effects on magnetism is relevant to a number of spin liquid candidate materials. Although commonly thought of as a route to spin glass behaviour, here we describe a system in which the structural disorder results in long-range antiferromagnetic order due to local symmetry breaking. Nd2ScNbO7is shown to have a dispersionless gapped excitation observed in other neodymium pyrochlores belowTN= 0.37 K through polarized and inelastic neutron scattering. However the dispersing spin waves are not observed. This excited mode is shown to occur in only 14(2)% of the neodymium ions through spectroscopy and is consistent with total scattering measurements as well as the magnitude of the dynamic moment 0.26(2)μB. The remaining magnetic species order completely into the all-in all-out Ising antiferromagnetic structure. This can be seen as a result of local symmetry breaking due disordered Sc+3and Nb+5ions about theA-site. From this work, it has been established thatB-site disorder restores the dipole-like behaviour of the Nd+3ions compared to the Nd2B2O7parent series.
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Affiliation(s)
- C Mauws
- Department of Chemistry, University of Manitoba, Winnipeg R3T 2N2, Canada
- Department of Chemistry, University of Winnipeg, Winnipeg R3B 2E9, Canada
| | - N Hiebert
- Department of Chemistry, University of Winnipeg, Winnipeg R3B 2E9, Canada
| | - M L Rutherford
- Department of Chemistry, University of Winnipeg, Winnipeg R3B 2E9, Canada
| | - H D Zhou
- Department of Physics and Astronomy, University of Tennessee-Knoxville, Knoxville 37996-1220, United States of America
- National High Magnetic Field Laboratory, Florida State University, Tallahassee 32306-4005, United States of America
| | - Q Huang
- Department of Physics and Astronomy, University of Tennessee-Knoxville, Knoxville 37996-1220, United States of America
| | - M B Stone
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States of America
| | - N P Butch
- Centre for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, MS 6100, Gaithersburg, Maryland 20899, United States of America
| | - Y Su
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich, Lichtenbergstrasse 1, 85747 Garching, Germany
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee 32306-4005, United States of America
| | - Z Yamani
- Canadian Neutron Beam Centre, National Research Council of Canada, Chalk River, K0J 1P0, Canada
| | - C R Wiebe
- Department of Chemistry, University of Manitoba, Winnipeg R3T 2N2, Canada
- Department of Chemistry, University of Winnipeg, Winnipeg R3B 2E9, Canada
- Department of Physics and Astronomy, McMaster University, Hamilton L8S 4M1, Canada
- Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
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Sarte PM, Aczel AA, Ehlers G, Stock C, Gaulin BD, Mauws C, Stone MB, Calder S, Nagler SE, Hollett JW, Zhou HD, Gardner JS, Attfield JP, Wiebe CR. Evidence for the confinement of magnetic monopoles in quantum spin ice. J Phys Condens Matter 2017; 29:45LT01. [PMID: 29049030 DOI: 10.1088/1361-648x/aa8ec2] [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: 06/07/2023]
Abstract
Magnetic monopoles are hypothesised elementary particles connected by Dirac strings that behave like infinitely thin solenoids (Dirac 1931 Proc. R. Soc. A 133 60). Despite decades of searching, free magnetic monopoles and their Dirac strings have eluded experimental detection, although there is substantial evidence for deconfined magnetic monopole quasiparticles in spin ice materials (Castelnovo et al 2008 Nature 326 411). Here we report the detection of a hierarchy of unequally-spaced magnetic excitations via high resolution inelastic neutron spectroscopic measurements on the quantum spin ice candidate [Formula: see text] [Formula: see text] [Formula: see text]. These excitations are well-described by a simple model of monopole pairs bound by a linear potential (Coldea et al Science 327 177) with an effective tension of 0.642(8) K [Formula: see text] at 1.65 K. The success of the linear potential model suggests that these low energy magnetic excitations are direct spectroscopic evidence for the confinement of magnetic monopole quasiparticles in the quantum spin ice candidate [Formula: see text] [Formula: see text] [Formula: see text].
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Affiliation(s)
- P M Sarte
- School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, United Kingdom. Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
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