Browsing by Author "Manuel, P"

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    Emergent frustration in co-doped β-Mn
    (American Physical Society, 2013-06-28) Paddison, JAM; Stewart, JR; Manuel, P; Courtois, P; McIntyre, GJ; Rainford, BD; Goodwin, AL
    We investigate low-temperature spin correlations in the metallic frustrated magnet beta-Mn1-xCox. Single-crystal polarized-neutron scattering experiments reveal the persistence of highly structured magnetic diffuse scattering and the absence of periodic magnetic order to T = 0.05 K. We employ reverse Monte Carlo refinements and mean-field theory calculations to construct an effective Hamiltonian which accounts for the magnetic scattering. The interactions we identify describe an emergent spin structure which mimics the triangular lattice antiferromagnet, one of the canonical models of frustrated magnetism. © 2013, American Physical Society.
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    Magnetic order in frustrated Kagome-Triangular lattice antiferromagnet NaBa2Mn3F11
    (American Physical Society, 2017-03) Hayashida, S; Ishikawa, H; Okamoto, Y; Okubo, T; Hiroi, Z; Avdeev, M; Manuel, P; Hagihala, M; Soda, M; Masuda, T
    We performed powder neutron diffraction experiments on NaBa2Mn3F11 [1], a model compound of \textit{Kagome-Triangular} lattice where three of six next-nearest neighbor interactions are non-negligible. More than 10 magnetic Bragg peaks are clearly observed below T= 2 K, meaning that the ground state is a magnetically ordered state. From indexing the magnetic Bragg peaks, magnetic propagation vector of \textbf{\textit{q}}0= (0, 0, 0) and two incommensurate vectors which are close to (1/3, 1/3, 0) are identified. Combination of representation analysis and Rietveld refinement reveals that the propagation vector of \textbf{\textit{q}}0 exhibits the 120º structure in the \textit{ab}-plane. Our calculation of the ground state suggests that the non-negligible magnetic dipolar interaction is responsible for the determined 120º structure in NaBa2Mn3F11. © 2021 American Physical Society
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    Magnetic state selected by magnetic dipole interaction in the kagome antiferromagnet NaBa2Mn3F11
    (American Physical Society, 2018-02-12) Hayashida, S; Ishikawa, H; Okamoto, Y; Okubo, T; Hiroi, Z; Avdeev, M; Manuel, P; Hagihala, M; Soda, M; Masuda, T
    We haved studied the ground state of the classical kagome antiferromagnet NaBa2Mn3F11. Strong magnetic Bragg peaks observed for d spacings shorter than 6.0 Å were indexed by the propagation vector of k0=(0,0,0). Additional peaks with weak intensities in the d-spacing range above 8.0 Å were indexed by the incommensurate vector of k1=[0.3209(2),0.3209(2),0] and k2=[0.3338(4),0.3338(4),0]. Magnetic structure analysis unveils a 120∘ structure with the tail-chase geometry having k0 modulated by the incommensurate vector. A classical calculation of the Heisenberg kagome antiferromagnet with antiferromagnetic second-neighbor interaction, for which the ground state a k0120∘ degenerated structure, reveals that the magnetic dipole-dipole (MDD) interaction including up to the fourth neighbor terms selects the tail-chase structure. The observed modulation of the tail-chase structure is attributed to a small perturbation such as the long-range MDD interaction or the interlayer interaction. ©2018 American Physical Society
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    β-Mn: emergent simplicity in a complex structure
    (Cornell University, 2013-02-04) Paddison, JAM; Stewart, JR; Manuel, P; Courtois, P; McIntyre, GJ; Rainford, BD; Goodwin, AL
    We investigate low-temperature spin correlations in the metallic frustrated magnet β-MnCo. Single-crystal polarised-neutron scattering experiments reveal the persistence of highly-structured magnetic diffuse scattering and the absence of periodic magnetic order to T = 0.05 K. We employ reverse Monte Carlo refinements and mean-field theory simulations to construct a simple effective Hamiltonian which accounts for the magnetic scattering. The interactions we identify describe an emergent spin structure which mimics the triangular lattice antiferromagnet. The observation of a simple collective magnetic state in a complicated crystal structure is surprising because it reverses the established paradigm of elaborate emergent states arising from many-body interactions on simple lattices. We suggest that structural complexity may provide a route to realising new states of correlated quantum matter.