Magnetic behaviour of synthetic Co2SiO4

2009 ◽  
Vol 65 (6) ◽  
pp. 664-675 ◽  
Author(s):  
Andrew Sazonov ◽  
Martin Meven ◽  
Vladimir Hutanu ◽  
Gernot Heger ◽  
Thomas Hansen ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Magnetic Structure ◽  
Magnetic Moment ◽  
Mirror Symmetry ◽  
Magnetic Moments ◽  
Exchange Interactions ◽  
Magnetic Behaviour ◽  
Relative Strength ◽  
Antiferromagnetic Ordering ◽  
Polarized Neutron

Synthetic Co2SiO4 crystallizes in the olivine structure (space group Pnma) with two crystallographically non-equivalent Co positions and shows antiferromagnetic ordering below 50 K. We have investigated the temperature variation of the Co2SiO4 magnetic structure by means of non-polarized and polarized neutron diffraction for single crystals. Measurements with non-polarized neutrons were made at 2.5 K (below T N), whereas polarized neutron diffraction experiments were carried out at 70 and 150 K (above T N) in an external magnetic field of 7 T parallel to the b axis. Additional accurate non-polarized powder diffraction studies were performed in a broad temperature range from 5 to 500 K with small temperature increments. Detailed symmetry analysis of the Co2SiO4 magnetic structure shows that it corresponds to the magnetic (Shubnikov) group Pnma, which allows the antiferromagnetic configuration (Gx , Cy , Az ) for the 4a site with inversion symmetry \bar{1} (Co1 position) and (0,Cy ,0) for the 4c site with mirror symmetry m (Co2 position). The temperature dependence of the Co1 and Co2 magnetic moments obtained from neutron diffraction experiments was fitted in a modified molecular-field model. The polarized neutron study of the magnetization induced by an applied field shows a non-negligible amount of magnetic moment on the oxygen positions, indicating a delocalization of the magnetic moment from Co towards neighbouring O owing to superexchange coupling. The relative strength of the exchange interactions is discussed based on the non-polarized and polarized neutron data.

scholarly journals Crystal and magnetic structures of R 2Ni1.78In compounds (R = Tb, Ho, Er and Tm)

2021 ◽  
Vol 77 (5) ◽  
pp. 824-832
Author(s):  
Stanisław Baran ◽  
Aleksandra Deptuch ◽  
Andreas Hoser ◽  
Bogusław Penc ◽  
Yuriy Tyvanchuk ◽  
...  
Keyword(s):  
Rare Earth ◽  
Neutron Diffraction ◽  
Magnetic Structure ◽  
Magnetic Moments ◽  
Symmetry Analysis ◽  
Crystalline Electric Field ◽  
Magnetic Structures ◽  
Antiferromagnetic Ordering ◽  
Crystal And Magnetic Structures ◽  
The Rare Earth

The crystal and magnetic structures in R 2Ni1.78In (R = Ho, Er and Tm) have been studied by neutron diffraction. The compounds crystallize in a tetragonal crystal structure of the Mo2FeB2 type (space group P4/mbm). At low temperatures, the magnetic moments, localized solely on the rare earth atoms, form antiferromagnetic structures described by the propagation vector k = [kx , kx , ½], with kx equal to ¼ for R = Er and Tm or 0.3074 (4) for R = Ho. The magnetic moments are parallel to the c axis for R = Ho or lie within the (001) plane for R = Er and Tm. The obtained magnetic structures are discussed on the basis of symmetry analysis. The rare earth magnetic moments, determined from neutron diffraction data collected at 1.6 K, are 6.5 (1) μB (Er) and 6.09 (4) μB (Tm), while in the incommensurate modulated magnetic structure in Ho2Ni1.78In the amplitude of modulation of the Ho magnetic moment is 7.93 (8) μB. All these values are smaller than those expected for the respective free R 3+ ions. A symmetry analysis of the magnetic structure in Tb2Ni1.78In is also included, as such information is missing from the original paper [Szytuła, Baran, Hoser, Kalychak, Penc & Tyvanchuk (2013). Acta Phys. Pol. A, 124, 994–997]. In addition, the results of magnetometric measurements are reported for Tm2Ni1.78In. The compound shows antiferromagnetic ordering below the Néel temperature of 4.5 K. Its magnetic properties are found to originate from magnetic moments localized solely on the thulium atoms (the nickel atoms remain non-magnetic in Tm2Ni1.78In). The reduction of rare earth magnetic moments in the ordered state in R 2Ni1.78In (R = Tb, Ho, Er and Tm) and the change in direction of the moments indicate the influence of the crystalline electric field (CEF) on the stability of the magnetic order in the investigated compounds.

scholarly journals The roles of chirality and polarity in novel multiferroics: MnSb2O6and Cu3Nb2O8

2014 ◽  
Vol 70 (a1) ◽  
pp. C386-C386
Author(s):  
Roger Johnson ◽  
Laurent Chapon ◽  
Kun Cao ◽  
Pascal Manuel ◽  
Alessandro Bombardi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Lattice ◽  
Magnetic Structure ◽  
Magnetic Moments ◽  
Polarization Vector ◽  
Exchange Interactions ◽  
Axial Rotation ◽  
Magnetic Polarity ◽  
Magnetic Exchange ◽  
Lattice Order

At room temperature Cu3Nb2O8 has a centrosymmetric, triclinic crystal structure. If cooled below 24 K, the copper magnetic moments order with a complex, generalized helicoidal magnetic structure that breaks inversion symmetry, giving rise to ferroelectricity. Unusually, the direction of the induced electric polarization vector with respect to the helicoidal spin rotation cannot be reconciled by conventional theories of magneto-electric coupling. Instead, we show that the observed multiferroic properties of Cu3Nb2O8 may be explained through a phenomenological analysis based upon coupling between the magnetic chirality, electric polarity, and a structural axial rotation. Trigonal MnSb2O6 crystallizes with a chiral crystal structure. Typically, magnetic materials with a chiral crystal lattice order with a chiral magnetic structure, where the magnetic exchange interactions and anisotropies follow the symmetry of the lattice. The magnetism of MnSi is a classic example of this scenario, in which exotic skyrmion phases emerge out of a helical magnetic state. To the contrary, we show that the low temperature magnetic structure of MnSb2O6 is cycloidal, described by a magnetic polarity as opposed to a chirality. We demonstrate through ab-initio calculations that this magnetic structure is in fact the ground state of the symmetric-exchange Heisenberg spin Hamiltonian, which has higher symmetry than the underlying crystal lattice. Furthermore, the phenomenology may be understood by considering the coupling between structural chirality, magnetic polarity, and a magnetic axial rotation. As a result, we predict MnSb2O6 to be multiferroic with a weak ferroelectric polarization.

Polarized Neutron Diffraction Study of CoS2. II Covalent Magnetic Moment around Sulfur Atoms

1976 ◽  
Vol 40 (4) ◽  
pp. 992-995 ◽  
Author(s):  
Akira Ohsawa ◽  
Yasuo Yamaguchi ◽  
Hiroshi Watanabe ◽  
Hiroki Itoh
Keyword(s):  
Neutron Diffraction ◽  
Diffraction Study ◽  
Magnetic Moment ◽  
Neutron Diffraction Study ◽  
Polarized Neutron

The anomalous paramagnetism of iron(III) NN-dialkyldithiocarbamates

1964 ◽  
Vol 17 (3) ◽  
pp. 294 ◽  
Author(s):  
AH White ◽  
R Roper ◽  
E Kokot ◽  
H Waterman ◽  
RL Martin
Keyword(s):  
Molecular Weight ◽  
Thermal Equilibrium ◽  
Room Temperature ◽  
Chemical Nature ◽  
Magnetic Moments ◽  
Chloroform Solution ◽  
Exchange Interactions ◽  
Magnetic Behaviour ◽  
Antiferromagnetic Exchange ◽  
Molecular Type

The magnetic moments of a series of 19 NN-disubstituted dithiocarbamates of iron(III), [Fe(S2C.NR?R")3], are anomalous in that their behaviour is neither "high-" nor "low-spin". Values of μeff. at room temperature lie between 2.62 and 5.83 B.M., the datum for each compound depending on the chemical nature of the substituents R' and R". This anomalous situation persists in benzene or chloroform solution. Cryoscopic and ebullioscopic molecular weight determinations establish that all the compounds are monomeric, which excludes the possibility that the magnetic behaviour arises from the presence of antiferromagnetic exchange interactions of either the inter- or intra-molecular type. These observations strongly support the early and generally overlooked work of Cambi who in 1932 proposed a thermal equilibrium between "magnetic isomers" of spins S = � and S = 5/2 to account for the origin of the magnetic anomaly.

scholarly journals Magnetic structure analysis of rare earth permanent magnet Sm2Fe17N3

2014 ◽  
Vol 70 (a1) ◽  
pp. C1460-C1460 ◽  
Author(s):  
Kotaro Saito ◽  
Nobuhito Inami ◽  
Yasuo Takeichi ◽  
Tetsuro Ueno ◽  
Ryoko Sagayama ◽  
...  
Keyword(s):  
Rare Earth ◽  
Neutron Diffraction ◽  
Magnetic Structure ◽  
Structure Analysis ◽  
Permanent Magnets ◽  
Nearest Neighbor ◽  
Magnetic Moments ◽  
High Coercivity ◽  
Diffraction Measurement ◽  
Fe Sites

Rare earth intermetallic compound Sm2Fe17N3 exhibits notalble magnetic properties such as high Curie temperature and high coercivity which are very suitable for permanent magnets [1,2]. Although microscopic magnetic structure is one of the basic information for magnetic materials, there is no report about the magnetic structure of Sm2Fe17N3 for our knowledge. This is because samarium's neutron absorption cross section is huge enough to make researchers hesitate to have neutron diffraction experiments of Sm compounds. We have carried out powder neutron diffraction measurement of Sm2Fe17N3 with a straightforward solution to the problem by taking long measurement time. Synchrotron x-ray diffraction measurements with single crystal has also been done to obtain initial crystal structure parameters for magnetic structure analysis and we have succeeded to analyze the magnetic structure of Sm2Fe17N3 at room temperature. Among four Fe sites in the unit cell, while one Fe site which is the nearest neighbor of nitrogen shows smaller magnetic moment than normal iron, two Fe sites show enhancement in their magnetic moments. This phenomenon can be understood as 'cobaltization' of Fe by the adjacent nitrogen through hybridization.

The magnetic structure of L10 ordered MnPt at room temperature determined using polarized neutron diffraction

2019 ◽  
Vol 6 (7) ◽  
pp. 076105 ◽  
Author(s):  
Danica Solina ◽  
Wolfgang Schmidt ◽  
Rainer Kaltofen ◽  
Cornelia Krien ◽  
Chih-Huang Lai ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Magnetic Structure ◽  
Room Temperature ◽  
Polarized Neutron

Internal magnetic structure of Mn12acetate by polarized neutron diffraction

2000 ◽  
Vol 12 (12) ◽  
pp. 2805-2810 ◽  
Author(s):  
R A Robinson ◽  
P J Brown ◽  
D N Argyriou ◽  
D N Hendrickson ◽  
S M J Aubin
Keyword(s):  
Neutron Diffraction ◽  
Magnetic Structure ◽  
Polarized Neutron

Neutron Diffraction Study on Magnetic Structure in Layered Manganite La2-2xSr1+2xMn2O7 (x=0.307)

2011 ◽  
Vol 172-174 ◽  
pp. 1301-1306 ◽  
Author(s):  
Hirosuke Sonomura ◽  
Tomoyuki Terai ◽  
Tomoyuki Kakeshita ◽  
Toyotaka Osakabe ◽  
Kazuhisa Kakurai ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Diffraction Study ◽  
Magnetic Structure ◽  
Magnetic Moment ◽  
Ground State ◽  
Neutron Diffraction Study ◽  
Layered Perovskite ◽  
Perovskite Manganite ◽  
Structure Changes ◽  
Ferromagnetic Structure

Magnetic structure in a layered perovskite manganite, La2-2xSr1+2xMn2O7 (x = 0.307) has been investigated by neutron diffraction measurements. We found that the ground state (at 4 K) has a ferromagnetic structure with magnetic moment of Mn ions being aligned in a direction inclined by 10 degree from the c-axis. The magnetic structure changes to a canted antiferromagnetic one (CAFM-I) at about 20 K and then to another canted antiferromagnetic one (CAFM-II) at about 80 K. Here the magnetic moment lies in the ab-plane in CAFM-II but not in CAFM-I. The magnetic structure then changes to an antiferromagnetic one with magnetic moment lies in the ab-plane at about 90 K, and then to a paramagnetic one at about 100 K.

Sign in / Sign up

Export Citation Format

Share Document