MAGNETIZATION PLATEAUS ON THE ZIGZAG LADDER WITH TWO-, AND THREE-SITE EXCHANGES

2007 ◽  
Vol 21 (20) ◽  
pp. 3567-3579 ◽  
Author(s):  
V. V. HOVHANNISYAN ◽  
L. N. ANANIKYAN ◽  
N. S. ANANIKIAN
Keyword(s):  
Magnetic Field ◽  
Partition Function ◽  
Strong Magnetic Field ◽  
Low Temperatures ◽  
Heisenberg Model ◽  
Spin Exchange ◽  
Exchange Interactions ◽  
Exact Results ◽  
Recursion Method ◽  
Exchange Parameters

We consider the Heisenberg model with two-, and three-spin exchange interactions on a zigzag ladder in a strong magnetic field. Using the recursion method for the partition function in Ising approximation we have found exact results for the magnetization. We have shown the existence of magnetization plateaus in the case of mutual two-, and three-spin exchanges at low temperatures and different exchange parameters. The system exhibits different magnetic behaviors, depending on the values of the exchange parameters.

scholarly journals Martensitic transformation in the systems based on Fe-Ni compositions in strong pulsed magnetic fields

2021 ◽  
pp. 22-29 ◽  
Author(s):  
I. Zolotarevskii
Keyword(s):  
Magnetic Field ◽  
Martensitic Transformation ◽  
Magnetic Fields ◽  
Temperature Dependence ◽  
Strong Magnetic Field ◽  
Low Temperatures ◽  
Strong Dependence ◽  
Magnetic Interaction ◽  
Iron Alloys ◽  
Pulsed Magnetic Fields

Purpose of work. To ascertain the causes of the abnormally large displacement of the martensitic point in steels and iron alloys in strong pulsed magnetic fields at low temperatures. Research methods. Generalization of experimental and theoretical investigations of the strong magnetic field influence on the martensitic transformation in steels and iron alloys, taking into account the magnetic state of austenite. The obtained results. The distributions of the martensitic point displacement ΔMS from the content of the main component - iron and the temperature of the martensitic γ → α- transformation beginning (martensitic point MS) in different experiments are obtained. It is shown that the obtained temperature dependence ΔMS(MS) in a strong magnetic field at low temperatures decomposes into two components, one of which correlates with the generalized Clapeyron-Clausius equations, and the other is opposite to it. In addition, it was found that steels and alloys with intense γ → α- transformation in a magnetic field contain at least 72.5% iron (wt), which at low temperatures in the fcc structure is antiferromagnetic. Scientific novelty. The anomalous temperature dependence of the distribution ΔMS(MS) in a strong magnetic field is explained on the basis of quantum representations of the magnetic interaction of atoms in the Fe-Ni system. This effect is associated with a number of other invar effects, in particular, with an abnormally large spontaneous and forced magnetostriction, a strong dependence of the resulting exchange integral on the interatomic distance. The point of view according to which in these alloys in a magnetic field γ → α- transformation occurs by the type of “magnetic first kind phase transformation” is substantiated. It is assumed that the nucleation of the martensitic phase in a magnetic field occurs in (at) local regions of γ- phase with disoriented atomic magnetic moments (with high compression and increased forced magnetostriction). Practical value. The information obtained in this work provides grounds for explaining the kinetic features of the transformation of austenite into martensite in steels and iron alloys.

scholarly journals Thermal Entanglement and Critical Behavior of Magnetic Properties on a Triangulated Kagomé Lattice

10.14311/1344 ◽  
2011 ◽  
Vol 51 (2) ◽  
Author(s):  
N. Ananikian ◽  
L. Ananikyan ◽  
L. Chakhmakhchyan ◽  
A. Kocharian
Keyword(s):  
Magnetic Field ◽  
Heisenberg Model ◽  
Quantum Phase Transitions ◽  
Exchange Interactions ◽  
Effective Field ◽  
Threshold Temperature ◽  
Kagome Lattice ◽  
Thermal Entanglement ◽  
Kagomé Lattice ◽  
Bogoliubov Inequality

The equilibrium magnetic and entanglement properties in a spin-1/2 Ising-Heisenberg model on a triangulated Kagomé lattice are analyzed by means of the effective field for the Gibbs-Bogoliubov inequality. The calculation is reduced to decoupled individual (clusters) trimers due to the separable character of the Ising-type exchange interactions between the Heisenberg trimers. The concurrence in terms of the three qubit isotropic Heisenberg model in the effective Ising field in the absence of a magnetic field is non-zero. The magnetic and entanglement properties exhibit common (plateau, peak) features driven by a magnetic field and (antiferromagnetic) exchange interaction. The (quantum) entangled and non-entangled phases can be exploited as a useful tool for signalling the quantum phase transitions and crossovers at finite temperatures. The critical temperature of order-disorder coincides with the threshold temperature of thermal entanglement.

THE QUANTUM REFRIGERATOR IN A TWO-QUBIT XXZ HEISENBERG MODEL

2013 ◽  
Vol 27 (13) ◽  
pp. 1350055 ◽  
Author(s):  
ERHAN ALBAYRAK
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Heisenberg Model ◽  
Exchange Parameter ◽  
Thermodynamic Quantities ◽  
Two Dimensional ◽  
Different Temperatures ◽  
Constant External Magnetic Field ◽  
Xxz Heisenberg Model ◽  
Exchange Parameters

The four-level entangled quantum refrigerator (QR) is studied in the XXZ Heisenberg model for the two-qubits. The Hamiltonian of the problem includes the exchange parameters Jx = Jy = J and Jz = αJ along the x-, y- and z-directions, respectively, and constant external magnetic field B in the z-direction. The parameter α is introduced into the model which controls the strength of the exchange parameter Jz in comparison to Jx and Jy, thus, our investigation of QR includes the XX (α = 0.0), XXX (α = 1.0) and XXZ (for other α's) Heisenberg models. The two-qubits are assumed to be in contact with two heat reservoirs at different temperatures. The concurrences for a two-qubit are used as a measure of entanglement and then the expressions for the amount of heat transferred, the work performed and the efficiency are derived. The contour, i.e., the isoline maps, and some two-dimensional plots of the above mentioned thermodynamic quantities are illustrated.

EFFECT OF A MAGNETIC FIELD ON THE BROKEN ELECTROWEAK SYMMETRY

2002 ◽  
Vol 17 (04) ◽  
pp. 561-573 ◽  
Author(s):  
E. RODRÍGUEZ QUERTS ◽  
A. MARTÍN CRUZ ◽  
H. PÉREZ ROJAS
Keyword(s):  
Magnetic Field ◽  
Symmetry Breaking ◽  
Strong Magnetic Field ◽  
Low Temperatures ◽  
Strong Field ◽  
Electroweak Symmetry ◽  
Rest Energy ◽  
Vector Bosons ◽  
Breaking Parameter ◽  
The Magnetic Field

We discuss the effect of a strong magnetic field in the behavior of the symmetry of an electrically neutral electroweak plasma. We analyze the case of a strong field and low temperatures as compared with the W rest energy. If the magnetic field is large enough, it is self-consistently maintained. It is shown that the charged vector bosons play the most important role, leading only to a decrease of the symmetry breaking parameter, the symmetry restoration not being possible.

EXACT RESULTS FOR THE ISING MODEL ON A 3–12 LATTICE

1989 ◽  
Vol 03 (08) ◽  
pp. 1237-1245
Author(s):  
K.Y. LIN
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Ising Model ◽  
Partition Function ◽  
Functional Relation ◽  
Interaction Parameters ◽  
Zero Field ◽  
Exact Results ◽  
Kagome Lattice ◽  
Kagomé Lattice

We consider the Ising model on a 3–12 lattice with magnetic field. An exact functional relation is established for the partition function and our result is a generalization of Giacomini’s work on the Kagomé lattice. We calculate the zero-field magnetic susceptibility when an appropriate relation among the interaction parameters is satisfied.

scholarly journals INFLUENCE OF ANISOTROPY AND MAGNETIC FIELD ON THERMAL ENTANGLEMENT IN HEISENBERG MODEL AND THERMODYNAMIC ANALYSIS OF MODEL

2017 ◽  
Vol 8 (2) ◽  
Author(s):  
Мilan Pantić ◽  
Nemanja Micić ◽  
Milica Pavkov Hrvojević ◽  
Slobodan Radošević ◽  
Petar Mali
Keyword(s):  
Magnetic Field ◽  
Thermodynamic Properties ◽  
Strong Magnetic Field ◽  
Thermodynamic Analysis ◽  
Interaction Parameter ◽  
Heisenberg Model ◽  
Thermal Entanglement ◽  
Dm Interaction ◽  
Analytical Expressions

The thermal entanglement in a two-qubit anisotropic Heisenberg XXZ system, also XYZ system, with Dzyaloshinskii-Moriya (DM) couplings in an inhomogenous magnetic field, was studied. The effects of these two kinds of anisotropies on the thermal entanglement have been studied in detail in the concept for concurrence, the measure of entanglement. The analytical expressions of concurrence are obtained for this model. It is found that the DM interaction can enhance thermal entanglement and can be efficiently controlled by the DM interaction parameter and ehchange interaction Jx, Jy and Jz. When D is large enough, the entanglement can exist for larger temperatures and strong magnetic field. We also analysed thermodynamic properties of Heisenberg model and the most important results were shown in the paper.

scholarly journals KAGOME APPROXIMATION FOR 3He ON HUSIMI LATTICE WITH TWO- AND THREE-SITE EXCHANGE INTERACTIONS

2010 ◽  
Vol 24 (30) ◽  
pp. 5913-5927 ◽  
Author(s):  
N. S. ANANIKIAN ◽  
V. V. HOVHANNISYAN ◽  
H. A. LAZARYAN
Keyword(s):  
Recursion Relation ◽  
Spin Exchange ◽  
Exchange Interactions ◽  
Model Parameters ◽  
Dynamic Approach ◽  
Saturation Field ◽  
The Third ◽  
Husimi Lattice ◽  
Site Exchange ◽  
Exchange Parameters

The Ising approximation of the Heisenberg model in a strong magnetic field, with two-, and three-spin exchange interactions are studied on a Husimi lattice. This model can be considered as an approximation of the third layer of 3 He absorbed on the surface of graphite (kagome lattice). Using dynamic approach, we have found exact recursion relation for the partition function. For different values of exchange parameters and temperature, the diagrams of magnetization are plotted and showed that magnetization properties of the model vary from ferromagnetic to antiferromagnetic depending on the value of model parameters. For antiferromagnetic case magnetization plateau at 1/3 of saturation field is obtained. Lyapunov exponent for recursion relation are considered and showed absence of bifurcation points in thermodynamic limit. The Yang–Lee zeros are analyzed in terms of neutral fixed points and showed that Yang–Lee zeros of the model are located on the arcs of the circle with the radius R = 1.

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