scholarly journals Zeroth-Order Nucleation Transition under Nanoscale Phase Separation

Symmetry ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2379
Author(s):  
Vyacheslav I. Yukalov ◽  
Elizaveta P. Yukalova
Keyword(s):  
Phase Separation ◽  
Stable State ◽  
Exchange Interactions ◽  
Ferromagnetic State ◽  
Ferromagnetic Phase ◽  
Zeroth Order ◽  
Nanoscale Phase Separation ◽  
Finite Concentration ◽  
Coexisting Phases ◽  
The Stability

Materials with nanoscale phase separation are considered. A system representing a heterophase mixture of ferromagnetic and paramagnetic phases is studied. After averaging over phase configurations, a renormalized Hamiltonian is derived describing the coexisting phases. The system is characterized by direct and exchange interactions and an external magnetic field. The properties of the system are studied numerically. The stability conditions define the stable state of the system. At a temperature of zero, the system is in a pure ferromagnetic state. However, at finite temperature, for some interaction parameters, the system can exhibit a zeroth-order nucleation transition between the pure ferromagnetic phase and the mixed state with coexisting ferromagnetic and paramagnetic phases. At the nucleation transition, the finite concentration of the paramagnetic phase appears via a jump.

scholarly journals Fеatures of exchange interactions of the B-sublattice ions in the La0,5Sr0,5Co1–x Nix O3–d system

2021 ◽  
Vol 65 (5) ◽  
pp. 539-545
Author(s):  
R. A. Lanovsky ◽  
A. V. Nikitsin ◽  
M. V. Bushinsky ◽  
N. V. Tereshko ◽  
O. S. Mantytskaya ◽  
...  
Keyword(s):  
Spin State ◽  
Magnetic Transition ◽  
Exchange Interactions ◽  
High Spin State ◽  
Unit Cell ◽  
Ferromagnetic Phase ◽  
National Academy Of Sciences ◽  
Cell Parameters ◽  
Ferromagnetic Interactions ◽  
The Stability

A comprehensive study of the crystal structure, magnetic and magnetotransport properties of the La0.5Sr0.5Co1–x Nix O3–d  cobaltite system (x = 0.1–0.16) was carried out. The X-ray measurement results indicate that the unit cell of all solid solutions of the system is cubic and is described by the space group Pm3m. It is found that with an increase in the 540     Doklady of the National Academy of Sciences of Belarus, 2021, vol. 65, no. 5, рр. 539–545 Ni content, the Curie temperature (TC) decreases from 230 to 180 K, as well as magnetization values. The magnetic transition is blurred across the field. The iodometric studies show that the concentration of Co4+ ions in all samples does not exceed 35 %. The chemical substitution of Co ions by Ni ones does not result in significant modification of the unit cell parameters, which may indicate a spin crossover of Co ions. The temperature dependence of resistivity is metallic in character, which indicates the stability of the main conducting ferromagnetic phase. The nature of exchange interactions of different signs between B-sublattice ions completely determines the behavior of the system. An increase in the content of Ni ions leads both to decrease the component of ferromagnetic exchange interactions between Co3+ ions in the intermediate spin state and to increase the fraction of antiferromagnetic and weaker ferromagnetic interactions. In addition, presumably the Co4+ ion can stabilize the high spin state of the closestCo3+ ion and in the next two coordination spheres it can stabilize the Co3+ ion in the low spin state, i. e. the ferromagnetic complexes Co4+–Co3+ (HS) are shielded by the diamagnetic shell of low spin Co3+ ions, which results in decreasing the magnetization values.

scholarly journals Role of higher-order exchange interactions for skyrmion stability

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Souvik Paul ◽  
Soumyajyoti Haldar ◽  
Stephan von Malottki ◽  
Stefan Heinze
Keyword(s):  
Exchange Interactions ◽  
Ferromagnetic State ◽  
Higher Order ◽  
Spin Model ◽  
Spin Interaction ◽  
Spintronic Devices ◽  
The Stability ◽  
Magnetic Skyrmions ◽  
Moriya Interaction

Abstract Transition-metal interfaces and multilayers are a promising class of systems to realize nanometer-sized, stable magnetic skyrmions for future spintronic devices. For room temperature applications, it is crucial to understand the interactions which control the stability of isolated skyrmions. Typically, skyrmion properties are explained by the interplay of pair-wise exchange interactions, the Dzyaloshinskii-Moriya interaction and the magnetocrystalline anisotropy energy. Here, we demonstrate that higher-order exchange interactions – which have so far been neglected – can play a key role for the stability of skyrmions. We use an atomistic spin model parametrized from first-principles and compare three different ultrathin film systems. We consider all fourth-order exchange interactions and show that, in particular, the four-site four spin interaction has a large effect on the energy barrier preventing skyrmion and antiskyrmion collapse into the ferromagnetic state. Our work opens perspectives to stabilize topological spin structures even in the absence of Dzyaloshinskii-Moriya interaction.

LANDSLIDE RISK MANAGEMENT IN THE COASTAL ZONE OF THE KUIBYSHEV RESERVOIR DUE THE DESIGN OF HIGH-SPEED LINE "MOSCOW-KAZAN"

2017 ◽  
Author(s):  
Nikolai Petrov ◽  
Nikolai Petrov ◽  
Inna Nikonorova ◽  
Inna Nikonorova ◽  
Vladimir Mashin ◽  
...  
Keyword(s):  
High Speed ◽  
Computational Models ◽  
Stable State ◽  
Landslide Risk ◽  
Kuibyshev Reservoir ◽  
Stepped Surface ◽  
The Stability ◽  
Landslide Slope ◽  
The Village

High-speed railway "Moscow-Kazan" by the draft crosses the Volga (Kuibyshev reservoir) in Chuvashia region 500 m below the village of New Kushnikovo. The crossing plot is a right-bank landslide slope with a stepped surface. Its height is 80 m; the slope steepness -15-16o. The authors should assess the risk of landslides and recommend anti-landslide measures to ensure the safety of the future bridge. For this landslide factors have been analyzed, slope stability assessment has been performed and recommendations have been suggested. The role of the following factors have been analyzed: 1) hydrologic - erosion and abrasion reservoir and runoff role; 2) lithologyc (the presence of Urzhum and Northern Dvina horizons of plastically deformable rocks, displacement areas); 3) hydrogeological (the role of perched, ground and interstratal water); 4) geomorphological (presence of the elemental composition of sliding systems and their structure in the relief); 5) exogeodynamic (cycles and stages of landslide systems development, mechanisms and relationship between landslide tiers of different generations and blocks contained in tiers). As a result 6-7 computational models at each of the three engineering-geological sections were made. The stability was evaluated by the method “of the leaning slope”. It is proved that the slope is in a very stable state and requires the following measures: 1) unloading (truncation) of active heads blocks of landslide tiers) and the edge of the plateau, 2) regulation of the surface and groundwater flow, 3) concrete dam, if necessary.

scholarly journals Study on instability failure mode and monitoring early warning standard of surrounding rock in fully weathered argillaceous sandstone section of large section tunnel

2019 ◽  
Vol 136 ◽  
pp. 04023
Author(s):  
Ming Zhao ◽  
Ke Li ◽  
Hong Yan Guo ◽  
KaiCheng Hua
Keyword(s):  
Limit State ◽  
Stable State ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Large Section ◽  
Rock Stability ◽  
Geological Conditions ◽  
Construction Step ◽  
The Face ◽  
The Stability

Based on the special geological conditions of a tunnel in Qingyuan section of Huizhou-Zhanzhou Expressway, FLAC3d numerical simulation software is used to simulate the rheological properties and instability of surrounding rock in large-section fully weathered sandstone section, and the stability and loss of surrounding rock are analyzed. The deformation of the dome and the face at steady state is analyzed. It is found that: 1) when the surrounding rock is in a stable state, the deformation curve of the dome is smooth. When the surrounding rock of the face is unstable, the front of the face appears ahead. Deformation should be first strengthened on the surrounding rock in front of the face. 2) The arched foot is an important part of the instability of the surrounding rock. In order to prevent the expansion of the collapsed part, the arched part should be reinforced. 3) In order to obtain the limit state of surrounding rock stability, the strength of surrounding rock is reduced, and the strength reduction coefficient corresponding to the displacement sudden point is taken as the safety factor of rock stability around the hole, and the stability safety coefficients of surrounding rock of each construction step are greater than 1.2. 4) The dynamic standard values of deformation control in the whole construction stage are obtained by analyzing the deformation curves of each data monitoring point with time in the corresponding time period of each construction step.

scholarly journals ToF-SIMS imaging of the nanoscale phase separation in polymeric light emitting diodes: Effect of nanostructure on device efficiency

The Analyst ◽  
2011 ◽  
Vol 136 (4) ◽  
pp. 716-723 ◽  
Author(s):  
Bang-Ying Yu ◽  
Che-Hung Kuo ◽  
Wei-Ben Wang ◽  
Guo-Ji Yen ◽  
Shin-ichi Iida ◽  
...  
Keyword(s):  
Phase Separation ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Nanoscale Phase Separation ◽  
Tof Sims ◽  
Device Efficiency

Prediction of vapour-liquid equilibrium: Theory, computer techniques and application to permanent gas mixtures at pressures in excess of 5 bar

1977 ◽  
Vol 30 (12) ◽  
pp. 2583 ◽  
Author(s):  
CP Hicks ◽  
CL Young
Keyword(s):  
Phase Separation ◽  
Fluid Model ◽  
Gas Mixtures ◽  
Liquid Equilibrium ◽  
Equal Area ◽  
Closed Equation ◽  
Coexisting Phases ◽  
Temperature And Pressure ◽  
Two Parameter ◽  
Theory And Experiment

A technique for calculating the composition of two coexisting phases in equilibrium at a given temperature and pressure is described. The method is applicable, in principle, to any one-fluid model and any two- parameter closed equation of state. The philosophy of the technique is similar to that used in previous work on critical points.��� Values of (∂G/∂x2)T,P are calculated for mole fraction compositions ranging from zero to unity in small steps in order to locate (∂G/∂x2)T,P loops. Around each loop there is a region of phase separation and the compositions of coexisting phases are found by the usual equal-area line technique. ��� The use of the method is briefly illustrated by comparison with the experimental results for simple gas mixtures. The agreement between theory and experiment is satisfactory.

Single nanoparticle of organic p-type and n-type hybrid materials: nanoscale phase separation and photovoltaic effect

2012 ◽  
Vol 22 (6) ◽  
pp. 2485-2490 ◽  
Author(s):  
Yong-baek Lee ◽  
Seok Ho Lee ◽  
Kihyun Kim ◽  
Jin Woo Lee ◽  
Kyung-Yeon Han ◽  
...  
Keyword(s):  
Phase Separation ◽  
Hybrid Materials ◽  
Photovoltaic Effect ◽  
Organic P ◽  
Nanoscale Phase Separation ◽  
Single Nanoparticle ◽  
P Type

scholarly journals Electrochemical Detection of Nanoscale Phase Separation in Binary Self-Assembled Monolayers

Langmuir ◽  
2005 ◽  
Vol 21 (10) ◽  
pp. 4615-4621 ◽  
Author(s):  
R. Carlisle Chambers ◽  
Christina E. Inman ◽  
James E. Hutchison
Keyword(s):  
Phase Separation ◽  
Electrochemical Detection ◽  
Self Assembled Monolayers ◽  
Nanoscale Phase Separation ◽  
Assembled Monolayers ◽  
Self Assembled

A model of Fe3+-kaolinite, Al3+-goethite, Al3+-hematite equilibria in laterites

Clay Minerals ◽  
1989 ◽  
Vol 24 (1) ◽  
pp. 1-21 ◽  
Author(s):  
F. Trolard ◽  
Y. Tardy
Keyword(s):  
Stability Field ◽  
Equilibrium Conditions ◽  
Dissolved Silica ◽  
Silica Activity ◽  
Proposed Model ◽  
Coexisting Phases ◽  
Activity Temperature ◽  
The Stability ◽  
Fe Substitution ◽  
Mineral Constituents

AbstractThe distribution of Fe3+-kaolinite, Al-goethite and Al-hematite and their contents of Fe and Al in bauxites and ferricretes are controlled by water activity, dissolved silica activity, temperature and particle size. The proposed model, based on ideal solid-solution equilibria in the Fe2O3-Al2O3-SiO2-H2O system, takes into account water and silica activities. By using the same considerations as those previously developed for the Fe2O3-Al2O3-H2O system, the model calculates the amounts of coexisting phases, Al or Fe substitution ratios in goethite, hematite or kaolinite, and the stability field distributions of the minerals under various conditions. Thermodynamic equilibrium conditions and element distributions within the mineral constituents are shown to be dependent on the parameters cited above. The model yields results compatible with natural observations on lateritic profiles.

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