XYZ-polarisation analysis of diffuse magnetic neutron scattering from single crystals

Schweika, W.

doi:10.1088/1742-6596/211/1/012026

Cited by 30 publications

(26 citation statements)

References 13 publications

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“…Thus, during the measurements, six different data sets were obtained for the neutron scattering intensity dependencies as functions of Q . The subsequent XYZ polarization analysis based on the Maleev–Blume theory was performed to separate the magnetic, nuclear incoherent, and nuclear coherent contribution to the total neutron scattering cross section. DNS data analysis was performed using the RMC method, which is implemented in the Spinvert program …”

Section: Methodsmentioning

confidence: 99%

Spin Correlations and Short‐Range Magnetic Order in the Honeycomb‐Layered Na₂Ni₂TeO₆

Korshunov

Safiulina

Курбаков

2019

Physica Status Solidi (b)

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An experimental study of long‐range magnetic order formation mechanisms in a layered structure with a honeycomb arrangement of the magnetic atoms Na2Ni2TeO6 is conducted. For the first time, the strong spin correlations are directly observed above the Neel temperature TN that is manifested in the presence of broad diffuse peaks on neutron diffraction patterns obtained with the XYZ polarization analysis. Due to the possibility of separating the magnetic, nuclear incoherent, and nuclear coherent contributions to the total neutron scattering cross section, it is unequivocally established that the observed diffuse scattering has magnetic nature. The spin‐pair correlation function is reconstructed by modeling diffuse neutron scattering on Na2Ni2TeO6 with reverse Monte Carlo method. The obtained results indicate 2D nature of the magnetic correlations, and moreover, the symmetry of short‐range magnetic state corresponds to long‐range zigzag‐type magnetic order in the honeycomb net, which is established earlier based on the theoretical calculations.

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Section: Methodsmentioning

confidence: 99%

Spin Correlations and Short‐Range Magnetic Order in the Honeycomb‐Layered Na₂Ni₂TeO₆

Korshunov

Safiulina

Курбаков

2019

Physica Status Solidi (b)

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“…A similar sample of magnetite core|manganese ferrite shell nanoparticles with better inter-particle ordering, but smaller sample volume and a slightly thinner manganese ferrite shell of 0.5 nm [26], was used to obtain the temperature dependence of the magnetization (M) and to estimate the inter-particle magnetic correlation length in remanence. For this sample, SANS polarization analysis of the neutron spin before and after scattering from the sample allows the structural and magnetic scattering to be unambiguously separated [28,[33][34][35]. The lowest-Q, structural SANS peak at 0.0842 Å −1 corresponds to the typical (111) inter-particle fcc reflection, and it is well modeled as an infinite fcc paracrystal with a distortion factor of 0.12 6 [36,37].…”

Section: Sample Characterizationmentioning

confidence: 99%

Spin waves across three-dimensional, close-packed nanoparticles

et al. 2018

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Inelastic neutron scattering is utilized to directly measure inter-nanoparticle spin waves, or magnons, which arise from the magnetic coupling between 8.4 nm ferrite nanoparticles that are self-assembled into a close-packed lattice, yet are physically separated by oleic acid surfactant. The resulting dispersion curve yields a physically-reasonable, non-negative energy gap only when the effective Q is reduced by the inter-particle spacing. This Q renormalization strongly indicates that the dispersion is a collective excitation between the nanoparticles, rather than originating from within individual nanoparticles. Additionally, the observed magnons are dispersive, respond to an applied magnetic field, and display the expected temperature-dependent Bose population factor. The experimental results are well explained by a limited parameter model which treats the three-dimensional ordered, magnetic nanoparticles as dipolar-coupled superspins.

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“…This instrument uses the XYZ method of polarization analysis, which allows one to extract information about diffuse magnetic correlations over a wide range of reciprocal space, including the directionality of ordered spins and possible existence of spin chirality 33 . Diffuse scattering correlations were explored in the [H H L] scattering plane of CoAl 2 O 4 with two sets of measurements, and main results are plotted in Fig.…”

Section: Coal2o4mentioning

confidence: 99%

“…In addition to confirming the magnetic origin of diffuse correlations, our results show that spin directions are largely isotropic. Following the analysis of Schweika 33 , we also compared spin-flip polarization in the x-direction to scattering taken with polarization reversed to search for signatures of chirality in this direction, but failed to see anything of note. Magnetic correlations are qualitatively similar above and below the temperature T = T * , consistent with our claim that diffuse scattering is largely the result of Lorentzian-like correlations, which we have shown exist at all temperatures.…”

Section: Coal2o4mentioning

confidence: 99%

Revisiting the ground state of CoAl2O4 : Comparison to the conventional antiferromagnet MnAl2O

MacDougall¹,

Aczel²,

Su³

et al. 2016

Phys. Rev. B

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The A-site spinel material, CoAl2O4, is a physical realization of the frustrated diamond-lattice antiferromagnet, a model in which unique incommensurate or 'spin-spiral liquid' ground states are predicted. Our previous single-crystal neutron scattering study instead classified it as a 'kineticallyinhibited' antiferromagnet, where the long ranged correlations of a collinear Néel ground state are blocked by the freezing of domain wall motion below a first-order phase transition at T* = 6.5 K. The current paper provides new data sets from a number of experiments, which support and expand this work in several important ways. We show that the phenomenology leading to the kinetically-inhibited order is unaffected by sample measured and instrument resolution, while new low temperature measurements reveal spin correlations are unchanging between T = 2 K and 250 mK, consistent with a frozen state. Polarized diffuse neutron measurements show several interesting magnetic features, which can be entirely explained by the existence of short-ranged Néel order. Finally, and crucially, this paper presents some of the first neutron scattering studies of single crystalline MnAl2O4, which acts as an unfrustrated analogue to CoAl2O4 and shows all the hallmarks of a classical antiferromagnet with a continuous phase transition to Néel order at TN = 39 K. Direct comparison between the two compounds indicates that CoAl2O4 is unique, not in the nature of high-temperature diffuse correlations, but rather in the nature of the frozen state below T * . The higher level of cation inversion in the MnAl2O4 sample indicates that this novel behavior is primarily an effect of greater next-nearest-neighbor exchange.PACS numbers: 75.30.Ds, 75.50.Lk, 78.70.Nx The A-site spinels, AB 2 X 4 with A magnetic, have seen a surge of interest in the past decade, due to a series of interesting experimental observations 1-15 and theoretical predictions of novel spin-liquid ground states [16][17][18][19][20] . Magnetic cations in these materials comprise a bi-partite diamond lattice, and novel behavior is argued to be the result of a competition between nearest (J 1 ) and nextnearest (J 2 ) neighbor superexchange interactions 2,21 . This is demonstrated explicitly by the calculations of Bergman et al. 16 , who have shown for spin-only materials that the collinear Néel structure favored by J 1 is progressively destabilized with increasing J 2 , until a Lifshitz point is encountered at J2 J1 = 1 8 . For greater J 2 , the ground state is predicted to be a novel 'spiral spin liquid' (SSL) state characterized by fluctuations between an infinitely degenerate set of incommensurate spin spirals, whose propagation wavevectors form a series of calculable manifolds in reciprocal space ('spiral surfaces'). Further calculations [16][17][18] predict that these mass degeneracies are lifted by low-lying thermal or quantum fluctuations, driving first-order phase transitions via the order-by-disorder mechanism 22 to either unique spin spiral or Néel ordered states, depending o...

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XYZ-polarisation analysis of diffuse magnetic neutron scattering from single crystals

Cited by 30 publications

References 13 publications

Spin Correlations and Short‐Range Magnetic Order in the Honeycomb‐Layered Na₂Ni₂TeO₆

Spin Correlations and Short‐Range Magnetic Order in the Honeycomb‐Layered Na₂Ni₂TeO₆

Spin waves across three-dimensional, close-packed nanoparticles

Revisiting the ground state of CoAl2O4 : Comparison to the conventional antiferromagnet MnAl2O

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XYZ-polarisation analysis of diffuse magnetic neutron scattering from single crystals

Cited by 30 publications

References 13 publications

Spin Correlations and Short‐Range Magnetic Order in the Honeycomb‐Layered Na2Ni2TeO6

Spin Correlations and Short‐Range Magnetic Order in the Honeycomb‐Layered Na2Ni2TeO6

Spin waves across three-dimensional, close-packed nanoparticles

Revisiting the ground state of CoAl2O4 : Comparison to the conventional antiferromagnet MnAl2O

Contact Info

Product

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Spin Correlations and Short‐Range Magnetic Order in the Honeycomb‐Layered Na₂Ni₂TeO₆

Spin Correlations and Short‐Range Magnetic Order in the Honeycomb‐Layered Na₂Ni₂TeO₆