| 1. |
- Paddison, Joseph A. M., et al.
(author)
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Spin correlations in Ca3Co2O6: Polarized-neutron diffraction and Monte Carlo study
- 2014
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In: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 90:1
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Journal article (peer-reviewed)abstract
- We present polarized-neutron diffraction measurements of the Ising-type spin-chain compound Ca3Co2O6 above and below the magnetic ordering temperature T-N. Below T-N, a clear evolution from a pure spin-density wave (SDW) structure to a mixture of SDW and commensurate antiferromagnet (CAFM) structures is observed on cooling. For a rapidly cooled sample, the majority phase at low temperature is the SDW, while if the cooling is performed sufficiently slowly, then the SDW and the CAFM structure coexist between 1.5 and 10 K. Above T-N, we use Monte Carlo methods to analyze the magnetic diffuse scattering data. We show that both intrachain and interchain correlations persist above T-N, but are essentially decoupled. Intrachain correlations resemble the one-dimensional ferromagnetic Ising model, while interchain correlations resemble the frustrated triangular-lattice antiferromagnet. Using previously published bulk property measurements and our neutron diffraction data, we obtain values of the ferromagnetic and antiferromagnetic exchange interactions and the single-ion anisotropy.
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| 2. |
- Jacobsen, Henrik, et al.
(author)
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Spin dynamics of the director state in frustrated hyperkagome systems
- 2021
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In: Physical Review B. - : American Physical Society. - 2469-9969 .- 2469-9950. ; 104:5
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Journal article (peer-reviewed)abstract
- We present an experimental study of the magnetic structure and dynamics of two frustrated hyperkagome compounds, Gd3Ga5O12 and Gd3Al5O12. It has previously been shown that Gd3Ga5O12 exhibits long-range correlations of multipolar directors that are formed from antiferromagnetic spins on loops of ten ions. Using neutron diffraction and reverse Monte Carlo simulations we prove the existence of similar magnetic correlations in Gd3Al5O12, showing the ubiquity of these complex structures in frustrated hyperkagome materials. Using inelastic neutron scattering we shed further light on the director state and the associated low-lying magnetic excitations. In addition, we have measured quasielastic dynamics that show evidence of spin diffusion. Finally, we present AC susceptibility measurements on both Gd3Ga5O12 and Gd3Al5O12, revealing a large difference in the low-frequency dynamics between the two otherwise similar compounds.
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| 3. |
- Paddison, Joseph A M, et al.
(author)
-
Hidden order in spin-liquid Gd₃Ga₅O₁₂.
- 2015
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In: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 350:6257, s. 179-181
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Journal article (peer-reviewed)abstract
- Frustrated magnetic materials are promising candidates for new states of matter because lattice geometry suppresses conventional magnetic dipole order, potentially allowing "hidden" order to emerge in its place. A model of a hidden-order state at the atomic scale is difficult to deduce because microscopic probes are not directly sensitive to hidden order. Here, we develop such a model of the spin-liquid state in the canonical frustrated magnet gadolinium gallium garnet (Gd3Ga5O12). We show that this state exhibits a long-range hidden order in which multipoles are formed from 10-spin loops. The order is a consequence of the interplay between antiferromagnetic spin correlations and local magnetic anisotropy, which allows it to be indirectly observed in neutron-scattering experiments.
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