scholarly journals Исследование фазовых переходов и термодинамических свойств модели Поттса с C-=SUB=-q-=/SUB=-=4 на гексагональной решетке с взаимодействиями вторых ближайших соседей

2020 ◽  
Vol 62 (3) ◽  
pp. 442
Author(s):  
М.К. Рамазанов ◽  
А.К. Муртазаев ◽  
М.А. Магомедов ◽  
М.К. Мазагаева
Keyword(s):  
Phase Transitions ◽  
Hexagonal Lattice ◽  
Magnetic Ordering ◽  
Nearest Neighbors ◽  
Magnetic Structures ◽  
First Order ◽  
The Monte Carlo Method ◽  
Cumulant Method ◽  
First Order Transition ◽  
Fourth Order Cumulant

Magnetic structures of the ground state, phase transitions and thermodynamic properties of the 2D ferromagnetic Potts model with the number of spin states q = 4 on a hexagonal lattice with next-nearest neighbors interactions are investigated by the Monte Carlo method based on the Wang-Landau algorithm. It is shown that taking into account the antiferromagnetic interactions of the next-nearest neighbors leads to the appearance of frustration and a violation of magnetic ordering. The orders of the phase transitions are investigated using the Binder fourth-order cumulant method and histogram analysis of data. It is established that a first-order transition is observed in the model being investigated.

scholarly journals Фазовая диаграмма модели Поттса с числом состояний спина q=4 на гексагональной решетке

2021 ◽  
Vol 63 (5) ◽  
pp. 622
Author(s):  
А.К. Муртазаев ◽  
М.К. Мазагаева ◽  
М.К. Рамазанов ◽  
М.А. Магомедов ◽  
А.А. Муртазаева
Keyword(s):  
Phase Transitions ◽  
Ground State ◽  
Nearest Neighbor ◽  
Hexagonal Lattice ◽  
Magnetic Ordering ◽  
Exchange Interactions ◽  
Antiferromagnetic Interaction ◽  
Two Dimensional ◽  
Magnetic Structures ◽  
First Order

We have carried out Monte Carlo investigations of the phase transitions, thermodynamic properties and ground-state magnetic structures in two-dimensional 4-state Potts model on a hexagonal lattice with the competing exchange interactions. Researches are carried out for the value of interaction of next-nearest neighbor in the range of 0.0≤r≤1.0. Taking into account of antiferromagnetic interaction of next-nearest neighbor is shown to lead to the violation of the magnetic ordering. The phase diagram of dependence of critical temperature on the value of interaction of next-nearest neighbor is plotted. Of the orders of phase transitions has been carried out. It is established that the phase transition of the first order is observed in the ranges of 0.0≤r≤0.2 and 0.7≤r≤1.0. In the range of 0.3≤r≤0.6 frustration are observed.

scholarly journals Фазовые переходы и термодинамические свойства модели Поттса с числом состояний спина q=4 на решетке кагоме

2020 ◽  
Vol 62 (8) ◽  
pp. 1278
Author(s):  
А.К. Муртазаев ◽  
Т.Р. Ризванова ◽  
М.К. Рамазанов ◽  
М.А. Магомедов
Keyword(s):  
Phase Transitions ◽  
Thermodynamic Properties ◽  
Fourth Order ◽  
Potts Model ◽  
Histogram Analysis ◽  
Spin States ◽  
First Order ◽  
Cumulant Method ◽  
First Order Transition ◽  
Fourth Order Cumulant

Phase transitions and thermodynamic properties of the 2D ferromagnetic Potts model with the number of spin states q = 4 on a kagome lattice are investigated by the Mote Carlo method based on the Wang-Landau algorithm. The orders of the phase transitions are investigated using the Binder fourth-order cumulant method and histogram analysis of data. It is established that a first-order transition is observed in the model being investigated.

scholarly journals Исследование влияния слабых магнитных полей на термодинамические свойства модели Поттса с числом состояний спина q=4 на гексагональной решетке

2022 ◽  
Vol 64 (2) ◽  
pp. 237
Author(s):  
М.К. Рамазанов ◽  
А.К. Муртазаев ◽  
М.А. Магомедов ◽  
М.К. Мазагаева ◽  
М.Р. Джамалудинов
Keyword(s):  
Hexagonal Lattice ◽  
Replica Exchange ◽  
Study Phase ◽  
Spin States ◽  
First Order ◽  
Weak Magnetic Fields ◽  
First Order Phase Transition ◽  
The Monte Carlo Method ◽  
First Order Phase ◽  
The Magnetic Field

The replica exchange algorithm of the Monte Carlo method was used to study phase transitions and thermodynamic properties of the two-dimensional Potts model with the number of spin states q = 4 on a hexagonal lattice in weak magnetic fields. The studies were carried out for the interval of the magnetic field value 0.0 ≤ Н ≤ 3.0 with a step of 1.0. It is found that a first-order phase transition is observed in the considered range of field values.

Dielectric Spectroscopy of (bis)Thiourea Pyridinium Bromide

2004 ◽  
Vol 59 (11) ◽  
pp. 857-860 ◽  
Author(s):  
A. Marczak ◽  
P. Czarnecki ◽  
S. Mielcarek
Keyword(s):  
Phase Transitions ◽  
Dielectric Spectroscopy ◽  
Solid Phase ◽  
Ion Dynamics ◽  
Pyridinium Bromide ◽  
First Order ◽  
New Information ◽  
First Order Transition ◽  
Dsc Method ◽  
Disorder Type

Policrystalline (bis)thiourea pyridinium bromide has been studied with dielectric spectroscopy and DSC method. New information about phase transitions in (bis)thiourea pyridinium bromide has been obtained and discussed. Two solid-solid phase transitions (at T2 = 150 K - first order transition of order-disorder type, and T1 = 180 K - second order) have been revealed. A change of the ion dynamics is observed at T2

MAGNETIC PHASE TRANSITIONS IN Ce(Fe1–xCox)2 SYSTEM

1993 ◽  
Vol 07 (01n03) ◽  
pp. 822-825 ◽  
Author(s):  
NAUSHAD ALI ◽  
XIANFENG ZHANG
Keyword(s):  
Phase Transitions ◽  
Magnetic Phase ◽  
Ac Susceptibility ◽  
Magnetic Phase Diagram ◽  
Ferromagnetic State ◽  
Magnetic Phase Transitions ◽  
Itinerant Electron ◽  
Electron Systems ◽  
First Order ◽  
First Order Transition

Re-entrant magnetic phase transitions in Ce(Fe1–xMx)2 systems (where M=Al, Ru, Co, etc.) are being investigated by various research groups. It has been observed that the system goes from a paramagnetic to ferromagnetic state followed by an almost complete loss of magnetization as the temperature is lowered. We have done systematic experimental measurements of magnetization, ac susceptibility, electrical resistivity, and thermal expansion on the Ce(Fe1–xCox)2 system. It is found that as the temperature is decreased, the system goes from para- to ferro- to antiferro-magnetic phase. The ferro- to antiferro-magnetic phase transition is a first order transition. Our experimental results are consistent with the magnetic phase diagram predictions by Moriya and Usami's theory of strongly interacting itinerant electron systems.

A simple model for phase transitions in monolayers and bilayers of lipid molecules

1978 ◽  
Vol 56 (3) ◽  
pp. 348-357 ◽  
Author(s):  
A. Caille ◽  
A. Rapini ◽  
M. J. Zuckermann ◽  
A. Cros ◽  
S. Doniach
Keyword(s):  
Phase Transitions ◽  
Simple Model ◽  
Hexagonal Lattice ◽  
Field Approximation ◽  
Van Der Waals Interactions ◽  
Melting Transition ◽  
Excluded Volume ◽  
Neighbourhood Effects ◽  
First Order ◽  
First Order Phase

A simple model for first order phase transitions in monomolecular systems is developed and applied to (i) the condensed mesophase – liquid mesophase chain melting transition of phospholipid mono- and bilayers and (ii) a cooperative chain lifting phase transition found in monolayers of diesters with two polar heads. The excluded volume interactions are included in the model by requiring the polar heads to lie on a two-dimensional hexagonal lattice. The attractive van der Waals interactions are assumed to act between averaged molecular configurations of different surface area per polar head. Both the attractive intermolecular interaction and the description of the neighbourhood of the molecules are analyzed in the molecular field approximation. It is shown that the neighbourhood effects are negligible for the chain melting transition, which can then be described by a [Formula: see text] Ising model. They are, however, shown to be important for the chain lifting transition. The last section contains applications to experimental data and comments on the possibility of extending the model to the description of phospholipid mono- and bilayers with impurities.

scholarly journals Исследование термодинамических свойств модели Изинга на объемно-центрированной кубической решетке с конкурирующими обменными взаимодействиями

2018 ◽  
Vol 60 (9) ◽  
pp. 1798
Author(s):  
А.К. Муртазаев ◽  
М.К. Рамазанов ◽  
М.А. Магомедов ◽  
Д.Р. Курбанова
Keyword(s):  
Phase Transition ◽  
Ground State ◽  
Exchange Interactions ◽  
Nearest Neighbors ◽  
Body Centered Cubic ◽  
Magnetic Structures ◽  
Cubic Lattice ◽  
The Monte Carlo Method ◽  
Antiferromagnetic Ising Model ◽  
Body Centered Cubic Lattice

AbstractUsing the Monte Carlo method, magnetic structures of the ground state and thermodynamic properties of the antiferromagnetic Ising model on a body-centered cubic lattice with competing exchange interactions are studied. The investigations are carried out for the ratio of the exchange interactions of next and nearest neighbors r = J _2/ J _1 = 2/3. All possible magnetic structures of the ground state for this ratio of exchange interactions have been obtained. It has been shown that at r = 2/3 the competition of exchange interactions does not lead to the appearance of frustration and degeneracy of the ground state. Based on the histogram data analysis, it has been shown that the phase transition of the second kind is observed in the model under study at r = 2/3.

Computer simulation of phase transitions of the Heisenberg antiferromagnetic model

2019 ◽  
pp. 25-31
Author(s):  
M.K. Ramazanov ◽  
A.K. Murtazaev
Keyword(s):  
Computer Simulation ◽  
Phase Transitions ◽  
Nearest Neighbor ◽  
Three Dimensional ◽  
Exchange Interactions ◽  
Nearest Neighbors ◽  
Neighbor Interaction ◽  
A Value ◽  
The Monte Carlo Method ◽  
Antiferromagnetic Model

Based on the replica algorithm by the Monte Carlo method, a computer simulation of the three-dimensional antiferromagnetic Heisenberg model is performed, taking into account the interactions of the first and second nearest neighbors. The phase transitions of this model are studied. The investigations were carried out for the ratios of the exchange interactions of the first and second nearest neighbors $r = J_2 / J_1$ in the range $0.0 \leq r \leq 1.0$. The phase diagram of the critical temperature dependence on a value of the next-nearest neighbor interaction is plotted.

scholarly journals First-order antiferromagnetic transitions of SrMn2P2 and CaMn2P2 single crystals containing corrugated-honeycomb Mn sublattices

2021 ◽  
Vol 118 (44) ◽  
pp. e2108724118
Author(s):  
N. S. Sangeetha ◽  
Santanu Pakhira ◽  
Qing-Ping Ding ◽  
Lennard Krause ◽  
Hyung-Cheol Lee ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Magnetic Susceptibility ◽  
Single Crystals ◽  
Nearest Neighbor ◽  
Second Order ◽  
Magnetic Structures ◽  
First Order ◽  
Slowing Down ◽  
First Order Transition ◽  
Antiferromagnetic Transitions

SrMn2P2 and CaMn2P2 are insulators that adopt the trigonal CaAl2Si2-type structure containing corrugated Mn honeycomb layers. Magnetic susceptibility χ and heat capacity versus temperature T data reveal a weak first-order antiferromagnetic (AFM) transition at the Néel temperature TN=53(1) K for SrMn2P2 and a strong first-order AFM transition at TN=69.8(3) K for CaMn2P2. Both compounds exhibit isotropic and nearly T-independent χ(T≤TN), suggesting magnetic structures in which nearest-neighbor moments are aligned at ≈120° to each other. The 31P NMR measurements confirm the strong first-order transition in CaMn2P2 but show critical slowing down above TN for SrMn2P2, thus also evidencing second-order character. The 31P NMR measurements indicate that the AFM structure of CaMn2P2 is commensurate with the lattice whereas that of SrMn2P2 is incommensurate. These first-order AFM transitions are unique among the class of (Ca, Sr, Ba)Mn2 (P, As, Sb, Bi)2 compounds that otherwise exhibit second-order AFM transitions. This result challenges our understanding of the circumstances under which first-order AFM transitions occur.

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