Nuclear and Magnetic Structures of K2NiF4-type Iron(III) Oxide Halides

2002 ◽  
Vol 755 ◽  
Author(s):  
Andrew L. Hector ◽  
Alexander I. MacDonald ◽  
Daniel J. Price ◽  
Mark T. Weller
Keyword(s):  
Magnetic Structure ◽  
Magnetic Ordering ◽  
Magnetic Structures ◽  
Antiferromagnetic Ordering ◽  
Ising Antiferromagnet ◽  
Layer Stacking

ABSTRACTK2NiF4-type iron(III) oxides show a very common form of magnetic ordering, XY antiferromagnetic ordering within the layers combined with layer stacking based on alignment of spins in alternate layers. The Ising antiferromagnet Ca2MnO4 has been reported to have a doubled c-axis (ca 24Å) in the magnetic structure and we have found a similar stacking in the XY antiferromagnet Sr2FeO3F. We show here that this unusual c-axis doubling is related to the exposure of the material to air and suggest that in both Sr2FeO3F and Ca2MnO4 it may be related to the occupation of interstitial sites.

scholarly journals Vibronic interaction as main reason of magnetic ordering in insulating manganites R1–xAxMnO3

2018 ◽  
Vol 185 ◽  
pp. 06005
Author(s):  
Liudmila Gonchar ◽  
Anatoliy Nikiforov
Keyword(s):  
Crystal Structure ◽  
Magnetic Structure ◽  
Magnetic Ordering ◽  
Vibronic Interaction ◽  
Magnetic Structures ◽  
Experimental Crystal ◽  
Experimental Crystal Structure

The model of orbitally dependent magnetic structure of charge ordered insulated manganites is proposed. The model is semi-phenomenological. It allows using a few parameters to describe possible magnetic structures of compounds. The experimental crystal structure of compounds also could be taken into account. The compounds LaMnO3, La1/2Ca1/2MnO3, La1/3Ca2/3MnO3, BiMnO3 are considered.

Magnetic structure of bornite, Cu5FeS4

1981 ◽  
Vol 59 (4) ◽  
pp. 535-539 ◽  
Author(s):  
M. F. Collins ◽  
G. Longworth ◽  
M. G. Townsend
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Magnetic Structure ◽  
Magnetic Phase ◽  
Magnetic Ordering ◽  
Neutron Powder Diffraction ◽  
Spin Rotation ◽  
Neutron Diffraction Data ◽  
X Ray ◽  
Antiferromagnetic Ordering

Neutron powder diffraction techniques have been used to investigate the magnetic structure of bornite, Cu5FeS4. Below the antiferromagnetic ordering temperature of 76 ± 2 K extra peaks appear in the diffraction pattern corresponding to magnetic ordering. The data are consistent with an antiferromagnetic alignment of iron atoms with moments of 4.4 ± 0.3 μB on the iron sites proposed by Koto and Morimoto on the basis of X-ray measurements of the crystal structure. Mössbauer and neutron diffraction data suggest that the second magnetic phase transition at 8 K arises from a spin rotation. Since the magnetic structure gives only superexchange paths between iron atoms through two or more anions, it is difficult to understand why the Néel temperature is so high without invoking small moments on copper atoms

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.

Magnetic Structure of Manganese Pyrophosphate and Copper Pyrophosphate

1972 ◽  
Vol 50 (24) ◽  
pp. 3079-3084 ◽  
Author(s):  
J. A. R. Stiles ◽  
C. V. Stager
Keyword(s):  
Phase Transition ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Magnetic Structure ◽  
Magnetic Structures

The magnetic structures of antiferromagnetic manganese pyrophosphate and copper pyrophosphate have been determined by single crystal neutron diffraction techniques. There have been two previous determinations of the structure of manganese pyrophosphate. The discrepancy between these results is explained by postulating a crystallographic phase transition.

Symmetry of Magnetic Structures: Magnetic Structure of Chalcopyrite

1958 ◽  
Vol 112 (6) ◽  
pp. 1917-1923 ◽  
Author(s):  
G. Donnay ◽  
L. M. Corliss ◽  
J. D. H. Donnay ◽  
N. Elliott ◽  
J. M. Hastings
Keyword(s):  
Magnetic Structure ◽  
Magnetic Structures

First-principles investigation of bandgap tailoring in tetragonal Bi2FeCrO6 by magnetic ordering and B-site-cation ordering

2019 ◽  
Vol 13 (01) ◽  
pp. 1950092
Author(s):  
Lijing Wei ◽  
Jianxin Guo ◽  
Li Guan ◽  
Baoting Liu
Keyword(s):  
First Principles ◽  
Magnetic Ordering ◽  
Stable Structure ◽  
Cation Ordering ◽  
First Principles Calculations ◽  
Antiferromagnetic Ordering ◽  
Long Time ◽  
Application Potential

The development of ferroelectric photovoltaic (FE-PV) materials has been limited for a long time due to their large bandgap. Many strategies for lowering the bandgap have been suggested to promote FE-PV properties. The effects of magnetic ordering and B-site-cation ordering to lower the bandgap of FE-PV are investigated in this paper using first-principles calculations. Results show that the most stable structure of tetragonal Bi2FeCrO6 ([Formula: see text]-Bi2[Formula: see text] is the AS1 structure (Fe/Cr alternate stacking ordering) with C-type antiferromagnetic ordering (defined as AC-[Formula: see text]-Bi2FeCrO6), which has a small bandgap, suggesting that AC-[Formula: see text]-Bi2FeCrO6 is among the FE-PV materials with the highest application potential.

Strukturen cäsiumhaltiger Fluoride, II1 Die Kristall- und Magnetische Struktur von CsFeF4 / Crystal and Magnetic Structure of CsFeF4

1974 ◽  
Vol 29 (3-4) ◽  
pp. 139-148 ◽  
Author(s):  
D. Babel ◽  
F. Wall ◽  
G. Heger
Keyword(s):  
Neutron Diffraction ◽  
Single Crystals ◽  
Magnetic Structure ◽  
Structure Determination ◽  
Mean Value ◽  
X Ray ◽  
Magnetic Structures ◽  
Powder Samples ◽  
Crystal And Magnetic Structure ◽  
Improved Model

The results of an X-ray structure determination on single crystals of CsFeF4 are reported. The compound crystallizes tetragonally with α = 7.794, c = 6.553 Å, z = 4, in spacegroup P4/nmm-D4h7 and is a hitherto unknown superstructure variant of the TlAlF4-type. Cesium exhibits 12-coordination (mean value Cs-F = 3.25 Å); the FeF6-octahedra are characteristically shortened normal to the FeF4⁻-layers (Fe-F = 1.962/1.861Å). An improved model is proposed and verified for a related structure of RbFeF4, showing the same features. Neutron diffraction studies on powder samples of CsFeF4 show that both compounds are identical as for their magnetic structures.

Superconductivity and Magnetic Ordering of Pr in CaLa1-xPrxBaCu3O7 System

1997 ◽  
Vol 11 (07) ◽  
pp. 323-331 ◽  
Author(s):  
V. P. S. Awana ◽  
Rajvir Singh ◽  
D. A. Landinez Tellez ◽  
J. M. Ferreira ◽  
J. Albino Aguiar ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Normal State ◽  
Ac Susceptibility ◽  
Magnetic Ordering ◽  
X Ray Diffraction ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Peak Intensity ◽  
Heat Capacity Measurements ◽  
A Minor

We present the results of superconductivity, normal state magnetic susceptibility and heat capacity measurements on the tetragonal CaLa 1-x Pr x BaCu 3 O 7 compound. Ac susceptibility measurements show that the transition temperature T c of the unsubstituted sample decreases with an increase in the Pr concentration. Normal state dc magnetic susceptibility measurements performed in an applied field of 0.5 T show a Curie–Weiss behaviour in terms of the paramagnetic moment of Pr. The effective paramagnetic moment of Pr appears to be intermediate between those of the free Pr 3+ and Pr 4+ ions. For the nonsuperconducting samples i.e., x = 0.70 and 1.0, we observe an antiferromagnetic ordering temperature T N of nearly 4 K and 8 K respectively. The X-ray diffraction results show that the CaPrBaCu 3 O 7 compound is free from other phases, having a minor (less than 8%, in terms of peak intensity) impurity phase. The lower T N (8 K) of PrBaCaCu 3 O 7 as compared to the known antiferromagnetic ordering temperature of 17 K for PrBa 2 Cu 3 O 7 indicates a less deleterious effect of Pr in the present case.

Magnetic Phase Diagram in Layered Perovskite Manganite La2-2xSr1+2xMn2O7 (0.313≤x≤0.350)

2006 ◽  
Vol 512 ◽  
pp. 183-188 ◽  
Author(s):  
Takeshi Murata ◽  
Tomoyuki Terai ◽  
Takashi Fukuda ◽  
Tomoyuki Kakeshita
Keyword(s):  
Phase Diagram ◽  
Magnetic Structure ◽  
Easy Axis ◽  
Magnetic Phase ◽  
Magnetic Phase Diagram ◽  
The Other ◽  
Layered Perovskite ◽  
Perovskite Manganites ◽  
Perovskite Manganite ◽  
Magnetic Structures

We have measured the magnetization as a function of temperature and magnetic field in layered perovskite manganites of La2-2xSr1+2xMn2O7 single crystals (x=0.313, 0.315, 0.320, 0.350) in order to know their magnetic structures. All the present manganites exhibit magnetic transitions from ferromagnetic to paramagnetic at 76K, 107K, 120K and 125K for x=0.313, 0.315, 0.320 and 0.350, respectively. For x=0.350 and 0.320, the magnetic structure is a planar ferromagnetism whose easy axis is in the ab-plane at all temperatures below the Curie temperature. On the other hand, for x=0.315 and 0.313, the magnetic structure is an uniaxial ferromagnetism whose easy axis is along the c-axis below 85K and 66K, respectively, and a planar ferromagnetism above the temperature. From the results described above, we made the detailed magnetic phase diagram of layered perovskite manganite La2-2xSr1+2xMn2O7 (0.313≤x≤0.350).

scholarly journals Symmetry constraints in frustrated magnets with strong magnetoelastic coupling

2014 ◽  
Vol 70 (a1) ◽  
pp. C516-C516
Author(s):  
Dmitry Khalyavin
Keyword(s):  
Representation Theory ◽  
Long Range ◽  
Ground States ◽  
Magnetic Ordering ◽  
Model Systems ◽  
Structural Motif ◽  
Geometrical Frustration ◽  
Magnetoelastic Coupling ◽  
Magnetic Structures ◽  
Symmetry Constraints

Geometrical frustration, related to the specific topology of certain crystal structures, plays a crucial role in forming exotic magnetic ground states. The presence of frustrated spins often leads to the suppression of long-range magnetic ordering and promotes short-range correlations due to fluctuations between nearly or totally degenerate ground states. The well-known structural topologies causing the presence of geometrical frustration are the three-dimensional pyrohlore and two-dimensional Kagome lattices. Compounds whose structural motif embraces these lattices are of great interest as model systems and have been the focus of numerous studies. In some cases, frustration is partially or entirely released by structural distortions through a strong magnetoelastic coupling and long-range magnetic order is established at a finite temperature. In the resulting distorted phases, complex noncollinear or partially disordered spin configurations can be observed. The phase transitions to the ordered state are quite often first order and may involve several irreducible representations of the paramagnetic space group and sometimes, like in the case of ZnCr2O4, even several propagation vectors which do not belong to the same star. The approach to determine magnetic structures in these systems, based on representation theory, should take into account the coupling free-energy invariants relating the magnetic and structural order parameters. Application of magnetic space groups and superspace groups is especially useful and can be efficiently combined with the representation theory. Based on specific examples, I will demonstrate how both approaches can be combined to provide symmetry constraints sufficient to solve complex magnetic structures in some geometrically frustrated systems.

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