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 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.

Magnetic Phase Transitions in the Two-Dimensional Random Mixture K2CuxCo1-xF4with Competing Exchange Interactions

1990 ◽  
Vol 59 (5) ◽  
pp. 1792-1800 ◽  
Author(s):  
Masayuki Itoh ◽  
Isao Yamada ◽  
Mamoru Ishizuka ◽  
Kiichi Amaya ◽  
Tatsuo Kobayashi ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Magnetic Phase ◽  
Exchange Interactions ◽  
Magnetic Phase Transitions ◽  
Two Dimensional ◽  
Random Mixture

Loss of classicality in the alternating spin-½/spin-1 chain, in the presence of next-neighbor couplings and Dzyaloshinskii-Moriya interactions

2022 ◽  
Author(s):  
Abhiroop Lahiri ◽  
Swapan K Pati
Keyword(s):  
Ground State ◽  
Nearest Neighbor ◽  
Spiral Structure ◽  
Exchange Interactions ◽  
Quantum Fluctuations ◽  
Wave Theory ◽  
Range Order ◽  
Density Matrix Renormalization Group ◽  
Density Matrix Renormalization ◽  
Spin Spiral

Abstract We have considered and alternating spin-½/spin-1 chain with nearest-neighbor (J1), next-nearest neighbor (J2) antiferromagnetic Heisenberg interactions along with z-component of the Dzyaloshinskii-Moriya(DM) (Dz) interaction. The Hamiltonian has been studied using (a) Linear Spin-Wave Theory(LSWT) and (b) Density Matrix Renormalization Group (DMRG). The system had been reported earlier as a classical ferrimagnet only when nearest neighbor exchange interactions are present. Both the antiferromagnetic next-nearest neighbor interactions and DM interactions introduce strong quantum fluctuations and due to which all the signatures of ferrimagnetism vanishes. We find that the nonzero J2 introduces strong quantum fluctuations in each of the spin sites due to which the z-components of both spin-1 and spin-1/2 sites average out to be zero. The ground state becomes a singlet. The presence of J1 along with Dzintroduces a short range order but develops long range order along the XY plane. J1 along with J2induces competing phases with structure factor showing sharp and wide peaks, at two different angles reflecting the spin spiral structure locally as well as in the underlying lattice. Interestingly, we find that the Dz term removes the local spin spiral structure in z-direction, while developing a spiral order in the XY plane.

On the Hysteresis of Adsorption on Solid Surfaces

1952 ◽  
Vol 5 (2) ◽  
pp. 288
Author(s):  
RG Wylie
Keyword(s):  
Phase Transitions ◽  
Solid Surface ◽  
Three Dimensional ◽  
Solid Surfaces ◽  
Two Dimensional ◽  
Capillary Effects ◽  
First Order ◽  
Adsorption Of Gases ◽  
First Order Phase ◽  
Hysteresis Phenomena

Hysteresis phenomena associated with the adsorption of gases on solid surfaces are usually explained in terms of three-dimensional capillary effects or with more or less unspecific reference to phase transitions. It is shown that hysteresis effects are to be expected when two dimensional phase transitions occur on solids. In the connection, the thermodynamic equation governing the equilibrium of small, incompressible two-dimensional phases is derived. Such phases can form on an imperfect solid surface in an irreversible manner and, as calculation shows, can contribute significantly to the hysteresis of adsorption. In some cases the phase change may be responsible for the whole effect. The diffuseness of first-order phase transitions may be due to the same mechanism.

scholarly journals Frustrations and phase transitions in magnets of various dimensionality

2018 ◽  
Vol 185 ◽  
pp. 11002
Author(s):  
Felix Kassan-Ogly ◽  
Alexey Proshkin
Keyword(s):  
Magnetic Field ◽  
Phase Transitions ◽  
External Magnetic Field ◽  
Specific Heat ◽  
Nearest Neighbor ◽  
Linear Chain ◽  
Exchange Interactions ◽  
Specific Model ◽  
Main Challenge ◽  
Transition Points

We studied magnetic orderings, phase transitions, and frustrations in the Ising, 3-state Potts and standard 4-state Potts models on 1D, 2D, and 3D lattices: linear chain, square, triangular, kagome, honeycomb, and body-centered cubic. The main challenge was to find out the causes of frustrations phenomena and those features that distinguish frustrated system from not frustrated ones. The spins may interrelate with one another via the nearest-neighbor, the next-nearest-neighbor or higher-neighbor exchange interactions and via an external magnetic field that may be either competing or not. For problem solving we mainly calculated the entropy and specific heat using the rigorous analytical solutions for Kramers-Wannier transfer-matrix and exploiting computer simulation, par excellence, by Wang-Landau algorithm. Whether a system is ordered or frustrated is depend on the signs and values of exchange interactions. An external magnetic field may both favor the ordering of a system and create frustrations. With the help of calculations of the entropy, the specific heat and magnetic parameters, we obtained the points and ranges of frustrations, the frustration fields and the phase transition points. The results obtained also show that the same exchange interactions my either be competing or noncompeting which depends on the specific model and the lattice topology.

scholarly journals Two-dimensional ground-state mapping of a Mott-Hubbard system in a flexible field-effect device

2019 ◽  
Vol 5 (5) ◽  
pp. eaav7282 ◽  
Author(s):  
Yoshitaka Kawasugi ◽  
Kazuhiro Seki ◽  
Satoshi Tajima ◽  
Jiang Pu ◽  
Taishi Takenobu ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Ground State ◽  
Field Effect ◽  
Mott Insulator ◽  
Two Dimensional ◽  
Superconducting Transition ◽  
Microscopic Mechanism ◽  
One Dimensional ◽  
First Order ◽  
Insulating Phase

A Mott insulator sometimes induces unconventional superconductivity in its neighbors when doped and/or pressurized. Because the phase diagram should be strongly related to the microscopic mechanism of the superconductivity, it is important to obtain the global phase diagram surrounding the Mott insulating state. However, the parameter available for controlling the ground state of most Mott insulating materials is one-dimensional owing to technical limitations. Here, we present a two-dimensional ground-state mapping for a Mott insulator using an organic field-effect device by simultaneously tuning the bandwidth and bandfilling. The observed phase diagram showed many unexpected features such as an abrupt first-order superconducting transition under electron doping, a recurrent insulating phase in the heavily electron-doped region, and a nearly constant superconducting transition temperature in a wide parameter range. These results are expected to contribute toward elucidating one of the standard solutions for the Mott-Hubbard model.

scholarly journals FIRST-ORDER QUANTUM CORRECTION TO THE GROUND-STATE ENERGY DENSITY OF TWO-DIMENSIONAL HARD-SPHERE BOSE ATOMS

2010 ◽  
Vol 24 (08) ◽  
pp. 1007-1019
Author(s):  
SANG-HOON KIM ◽  
MUKUNDA P. DAS
Keyword(s):  
Energy Density ◽  
Ground State Energy ◽  
Ground State ◽  
Hard Sphere ◽  
Quantum Correction ◽  
State Energy ◽  
Spatial Dimension ◽  
Effective Field ◽  
Two Dimensional ◽  
First Order

Divergence exponents of the first-order quantum correction of a two-dimensional hard-sphere Bose atoms are obtained by an effective field theory method. The first-order correction to the ground-state energy density with respect to the zeroth-order is given by [Formula: see text], where D is the spatial dimension, and γ is the gas parameter (γ = naD). As D →2, α = α′ = 1. We show that the first-order quantum correction of the energy density is not perturbative in low dimensions of D < 2.2 regardless of any gas parameter which is much less than unity.

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