Magnetic Order in Quaternary NiMnGe:T (T = Cr, Ti) Compounds

The work reports the results of neutron diffraction measurements of NiMnGe:T systems where T is Cr or Ti. All investigated compounds have the helicoidal magnetic structure with the propagation vector k = (ka,0,0). The values of the ka component decrease with increasing Cr content and increase with increasing Ti content. For all compounds, except the sample with x = 0.18 in Cr-system, the helicoidal order is stable up to the Néel temperature. The obtained data are analysed based on simple model in which the magnetic interactions are described by two exchange integrals J1 > 0 for first and J2 < 0 for second neighbouring moments. This model clears up different dependence of ka component in different systems.

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Magnetoelastic driven Negative Thermal Expansion in a Framework Antiferromagnet

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s205327331409723x ◽

2014 ◽

Vol 70 (a1) ◽

pp. C276-C276

Author(s):

Paul Saines ◽

Phillip Barton ◽

Marek Jura ◽

Kevin Knight ◽

Anthony Cheetham

Keyword(s):

Thermal Expansion ◽

Low Temperature ◽

Neutron Diffraction ◽

Magnetic Structure ◽

Magnetic Order ◽

Variable Temperature ◽

Negative Thermal Expansion ◽

Orthorhombic Phase ◽

Two Dimensions ◽

Magnetic Interactions

Metal-organic frameworks (MOFs) have recently attracted great attention for their multiferroic, magnetocaloric and low dimensional magnetic order. These properties depend on the precise magnetic interactions in frameworks and a deeper understanding of the coupling between the lattice of these materials and their magnetic order is required to underpin the future developments of these promising compounds. Neutron diffraction is the ideal technique for such studies but its application to studies of the magnetic structure of MOFs has been limited to date due to challenges in solving the structure of these dilute yet complex magnetic compounds. We have recently examined the magnetic properties and structure of a new dicarboxylate framework, cobalt adipate, Co(C6H8O4), which adopts P21/c monoclinic symmetry.[1] This compound has been found to order antiferromagnetically at low temperature and fits to neutron diffraction data have shown it adopts Pb21/c magnetic symmetry. Its magnetic structure features sheets of Co cations coupled antiferromagnetically in two dimensions through carboxylate groups. The emergence of this order is accompanied by magnetoelastic coupling, which drives anisotropic negative thermal expansion along the a-axis at low temperature. This is the first evidence for such behaviour in a MOF and we find that both this behaviour and the spin orientation in this material are controlled by the presence of weak ferromagnetic dipole-dipole coupling between the layers of tetrahedral cobalt. Variable temperature high resolution synchrotron X-ray and neutron powder diffraction have also revealed that the monoclinic angle of Co adipate decreases on cooling, passing through a metrically orthorhombic phase without any indication of a phase transition. This unusual behaviour has been rationalised by examining the thermal expansion of the framework along its principal axis, highlighting the importance of such analysis in low symmetry materials.

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Magnetic structure, magnetic interactions and metamagnetism in terbium iron borate TbFe3(BO3)4: a neutron diffraction and magnetization study

Journal of Physics Condensed Matter ◽

10.1088/0953-8984/19/19/196227 ◽

2007 ◽

Vol 19 (19) ◽

pp. 196227 ◽

Cited By ~ 52

Author(s):

C Ritter ◽

A Balaev ◽

A Vorotynov ◽

G Petrakovskii ◽

D Velikanov ◽

...

Keyword(s):

Neutron Diffraction ◽

Magnetic Structure ◽

Magnetic Interactions ◽

Iron Borate ◽

Magnetization Study

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Magnetic structure of solid 3He observed by neutron diffraction

Canadian Journal of Physics ◽

10.1139/p87-212 ◽

1987 ◽

Vol 65 (11) ◽

pp. 1343-1345 ◽

Cited By ~ 2

Author(s):

A. Benoit ◽

J. Bossy ◽

J. Flouquet ◽

J. Schweizer

Keyword(s):

Neutron Diffraction ◽

Magnetic Structure ◽

Magnetic Ordering ◽

Antiferromagnetic Order ◽

Magnetic Signal ◽

Propagation Vector ◽

Ordering Transition ◽

First Time ◽

Solid 3He

Neutron-diffraction measurements have been performed on a 3He crystal below the magnetic-ordering transition. The measurements have allowed, for the first time, the observation of a magnetic signal. They prove directly the occurrence of an antiferromagnetic order with a propagation vector (1/2, 0, 0).

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Non-collinear magnetic structure of manganese quadruple perovskite CdMn7O12

Scientific Reports ◽

10.1038/srep45939 ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 3

Author(s):

H. Guo ◽

M. T. Fernández-Díaz ◽

L. Zhou ◽

Y. Yin ◽

Y. Long ◽

...

Keyword(s):

Phase Transition ◽

Phase Separation ◽

Neutron Diffraction ◽

Magnetic Structure ◽

Structural Phase Transition ◽

Magnetic Moments ◽

Structural Phase ◽

Powder Neutron Diffraction ◽

Propagation Vector ◽

Absorbing Material

Abstract We report on the magnetic structure of CdMn7O12 determined by powder neutron diffraction. We were able to measure the magnetic structure of this Cd containing and highly neutron absorbing material by optimizing the sample geometry and by blending the CdMn7O12 with Aluminum powder. Below its Néel temperature T N1 all magnetic reflections can be indexed by a single commensurate propagation vector k = (0, 0, 1). This is different to the case of CaMn7O12 where the propagation vector is incommensurate and where an in-plane helical magnetic structure has been found. We observe a commensurate non-collinear magnetic structure in CdMn7O12 with in-plane aligned magnetic moments resembling the ones in CaMn7O12. However, the commensurate propagation vector prevents the appearance of a helical magnetic structure in CdMn7O12. Finally, we also observe a third structural phase transition below ~60 K that can be attributed to phase separation.

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Multi-k magnetic order in Ca3CuNi2(PO4)4: irrep approach and Shubnikov symmetry

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314085416 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C1458-C1458

Author(s):

Vladimir Pomjakushin

Keyword(s):

Experimental Data ◽

Magnetic Structure ◽

Magnetic Order ◽

Quantum Spin ◽

Expectation Values ◽

Space Group ◽

Magnetic Structures ◽

Propagation Vector ◽

Antiferromagnetic Structure ◽

Low Dimensional

The multi-k magnetic structures with propagation vectors k being the arms of the propagation vector star rarely can be justified experimentally. We show that the antiferromagnetic structure in the low dimensional quantum spin trimer system Ca3CuNi2(PO4)4 is based on the full star of propagation vector k=[1/2,1/2,0] of the paramagnetic space group C2/c. The relation between representation analysis in the propagation vector formalism and Shubnikov magnetic space group (MSG) symmetry is examined in details. A symmetry restrictive MSG that excellently fits the experimental data can be constructed only with the use of the full star. The magnetic structure is further supported by the calculations of the spin expectation values of the isolated Ni-Cu-Ni trimer with realistic Hamiltonian.

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Magnetic Structures of Some Multiferroics

KnE Materials Science ◽

10.18502/kms.v1i1.575 ◽

2016 ◽

Vol 1 (1) ◽

pp. 135

Author(s):

M.A. Semkin ◽

N.V. Urusova ◽

D.G. Kellerman ◽

A.P. Nosov ◽

S. Lee ◽

...

Keyword(s):

Magnetic Structure ◽

Magnetic Moment ◽

Single Phase ◽

Magnetic Order ◽

Magnetic Structures ◽

Propagation Vector ◽

Ferrimagnetic Structure ◽

Crystal And Magnetic Structures

We studied crystal and magnetic structures of some composite and single-phase multiferroics: (x)MFe2O4 + (1-x)BaTiO3, Ni3-yCoyV2O8, and Bi0.9Ba0.1Fe0.9Ti0.1O3. Composite multiferroics (x)MFe2O4 + (1-x)BaTiO3 with x = (0.2; 0.3; 0.4) and M = (Ni, Co) have ferrimagnetic structure, which is described by the propagation vector k = 0. Oxides Ni3-yCoyV2O8 with y = (0.1; 0.3; 0.5) possess a modulated magnetic structure, described by the vector k = (δ, 0, 0), where δ = 0.283 and 0.348 at 7.4 K for y = 0.1 and 0.5, respectively. In the Bi0.9Ba0.1Fe0.9Ti0.1O3 multiferroic a magnetic order is destroyed at 600 K and the Fe-ion magnetic moment decreases from µ = 3.46(5) μB at 300 K to zero at 600 K.

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