Ising Model Simulation Of Magnetic Structures IN A Zn-Mg-Ho Structure Model

1998 ◽  
Vol 553 ◽  
Author(s):  
S. Matsuo ◽  
T. Ishimasa ◽  
H. Nakano
Keyword(s):  
Scattering Amplitudes ◽  
Magnetic Structure ◽  
Long Range ◽  
Low Temperatures ◽  
Model Simulation ◽  
Structure Model ◽  
Patterson Function ◽  
Magnetic Structures ◽  
Shortest Distance ◽  
Diffraction Patterns

AbstractSimulated annealing calculations were performed for Ising spins on Ho sites under Ruderman-Kittel-Kasuya-Yosida-like alternating exchange interactions for an icosahedral Zn-Mg-Ho structure model with intent to investigate the magnetic structures at low temperatures. Magnetic structures were analyzed by means of a Patterson function and diffraction patterns arising from spin-dependent scattering amplitudes. The diffraction patterns from the magnetic structure consist of spots at low temperatures in the case of an antiferromagnetic interaction for the shortest distance (3.37 Å) and a ferromagnetic interaction for the second shortest distance (5.46 Å). The Patterson maps indicate a long-range antiferromagnetic correlation. These facts mean that a long-range ordered magnetic structure is realized at low temperatures. The contrast of the diffraction patterns is different from the patterns arising from the spin-independent scattering amplitudes from the Ho sites. A reversed sign interaction, ferromagnetic for the shortest distance and antiferromagnetic for the second shortest distance, results in broad intensity minima in the magnetic diffraction at the positions of strong spots in the spin-independent diffraction by lattice sites. It corresponds to the degradation of the long-range correlation.

Interpretation of irradiation-induced changes in electron diffractograms and images of extinction contours at low temperatures

1984 ◽  
Vol 42 ◽  
pp. 268-269
Author(s):  
E. Knapek ◽  
H. Formanek ◽  
G. Lefranc ◽  
I. Dietrich
Keyword(s):  
Low Temperatures ◽  
Carbon Films ◽  
Organic Crystals ◽  
Wide Spread ◽  
Lens System ◽  
Preparation Conditions ◽  
Thin Carbon ◽  
Electron Diffractograms ◽  
Diffraction Patterns ◽  
Induced Changes

A few years ago results on cryoprotection of L-valine were reported, where the values of the critical fluence De i.e, the electron exposure which decreases the intensity of the diffraction reflections by a factor e, amounted to the order of 2000 + 1000 e/nm2. In the meantime a discrepancy arose, since several groups published De values between 100 e/nm2 and 1200 e/nm2 /1 - 4/. This disagreement and particularly the wide spread of the results induced us to investigate more thoroughly the behaviour of organic crystals at very low temperatures during electron irradiation.For this purpose large L-valine crystals with homogenuous thickness were deposited on holey carbon films, thin carbon films or Au-coated holey carbon films. These specimens were cooled down to nearly liquid helium temperature in an electron microscope with a superconducting lens system and irradiated with 200 keU-electrons. The progress of radiation damage under different preparation conditions has been observed with series of electron diffraction patterns and direct images of extinction contours.

Ordering in Ni4Mo by TEM and APFIM

1987 ◽  
Vol 45 ◽  
pp. 214-215
Author(s):  
E.A. Kenik ◽  
T.A. Zagula ◽  
M.K. Miller ◽  
J. Bentley
Keyword(s):  
Electron Irradiation ◽  
Low Temperatures ◽  
Short Range ◽  
Atom Probe ◽  
Range Order ◽  
Considerable Time ◽  
Probe Field ◽  
Disordered Phase ◽  
Transmission Electron ◽  
Diffraction Patterns

The state of long-range order (LRO) and short-range order (SRO) in Ni4Mo has been a topic of interest for a considerable time (see Brooks et al.). The SRO is often referred to as 1½0 order from the apparent position of the diffuse maxima in diffraction patterns, which differs from the positions of the LRO (D1a) structure. Various studies have shown that a fully disordered state cannot be retained by quenching, as the atomic arrangements responsible for the 1½0 maxima are present at temperatures above the critical ordering temperature for LRO. Over 20 studies have attempted to identify the atomic arrangements associated with this state of order. A variety of models have been proposed, but no consensus has been reached. It has also been shown that 1 MeV electron irradiation at low temperatures (∼100 K) can produce the disordered phase in Ni4Mo. Transmission electron microscopy (TEM), atom probe field ion microscopy (APFIM), and electron irradiation disordering have been applied in the current study to further the understanding of the ordering processes in Ni4Mo.

Low-frequency vibrational spectroscopy: a new tool for revealing crystalline magnetic structures in iron phosphate crystals

2021 ◽  
Vol 23 (39) ◽  
pp. 22241-22245
Author(s):  
Zihui Song ◽  
Xudong Liu ◽  
Anish Ochani ◽  
Suling Shen ◽  
Qiqi Li ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Long Range ◽  
Vibrational Spectroscopy ◽  
Strong Dependence ◽  
Low Frequency ◽  
Lithium Ion ◽  
Iron Phosphate ◽  
Promising Material ◽  
Vibrational Dynamics ◽  
Magnetic Structures

In this report, the strong-dependence of low-frequency (terahertz) vibrational dynamics on weak and long-range forces in crystals is leveraged to determine the bulk magnetic configuration of iron phosphate – a promising material for cathodes in lithium ion batteries.

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

Long-range exchange interactions in epitaxial layered magnetic structures

1996 ◽  
Vol 221 (1-4) ◽  
pp. 357-365 ◽  
Author(s):  
P. Grünberg ◽  
J.A. Wolf ◽  
R. Schäfer
Keyword(s):  
Long Range ◽  
Exchange Interactions ◽  
Magnetic Structures

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.

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).

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