Critical line of the square-lattice antiferromagnetic Ising model in a magnetic field

1990 ◽  
Vol 144 (3) ◽  
pp. 123-126 ◽  
Author(s):  
X.N. Wu ◽  
F.Y. Wu
Keyword(s):  
Magnetic Field ◽  
Ising Model ◽  
Critical Line ◽  
Square Lattice ◽  
Antiferromagnetic Ising Model

scholarly journals Anisotropic scaling of the two-dimensional Ising model II: surfaces and boundary fields

2020 ◽  
Vol 8 (3) ◽  
Author(s):  
Hendrik Hobrecht ◽  
Fred Hucht
Keyword(s):  
Ising Model ◽  
Boundary Conditions ◽  
Scaling Limit ◽  
Finite Size ◽  
Square Lattice ◽  
Conformal Field ◽  
Anisotropic Scaling ◽  
Finite Lattices ◽  
Antiferromagnetic Ising Model ◽  
Boundary Fields

Based on the results published recently [SciPost Phys. 7, 026 (2019)], the influence of surfaces and boundary fields are calculated for the ferromagnetic anisotropic square lattice Ising model on finite lattices as well as in the finite-size scaling limit. Starting with the open cylinder, we independently apply boundary fields on both sides which can be either homogeneous or staggered, representing different combinations of boundary conditions. We confirm several predictions from scaling theory, conformal field theory and renormalisation group theory: we explicitly show that anisotropic couplings enter the scaling functions through a generalised aspect ratio, and demonstrate that open and staggered boundary conditions are asymptotically equal in the scaling regime. Furthermore, we examine the emergence of the surface tension due to one antiperiodic boundary in the system in the presence of symmetry breaking boundary fields, again for finite systems as well as in the scaling limit. Finally, we extend our results to the antiferromagnetic Ising model.

PHASE BOUNDARY AND UNIVERSALITY OF THE TRIANGULAR LATTICE ANTIFERROMAGNETIC ISING MODEL

1992 ◽  
Vol 06 (17) ◽  
pp. 2913-2924 ◽  
Author(s):  
JAE DONG NOH ◽  
DOOCHUL KIM
Keyword(s):  
Magnetic Field ◽  
Ising Model ◽  
Phase Boundary ◽  
Triangular Lattice ◽  
Central Charge ◽  
Universality Class ◽  
Zero Field ◽  
Crossover Effect ◽  
Matrix Methods ◽  
Antiferromagnetic Ising Model

Transfer matrix methods are used to locate accurate phase boundary of the triangular lattice antiferromagnetic Ising model in magnetic field. Universal quantities such as the central charge and the first few scaling dimensions are obtained along the phase boundary except near the zero field point where the crossover effect degrades convergence. Numerical results are fully consistent with the operator content of the 3-state Potts model indicating that whole phase boundary belongs to the 3-state Potts universality class.

scholarly journals Weak Singularities of the Isothermal Entropy Change as the Smoking Gun Evidence of Phase Transitions of Mixed-Spin Ising Model on a Decorated Square Lattice in Transverse Field

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1533
Author(s):  
Jozef Strečka ◽  
Katarína Karl’ová
Keyword(s):  
Magnetic Field ◽  
Phase Transitions ◽  
Ising Model ◽  
Magnetocaloric Effect ◽  
Entropy Change ◽  
Transverse Magnetic ◽  
Continuous Phase ◽  
Square Lattice ◽  
Mixed Spin ◽  
Weak Singularities

The magnetocaloric response of the mixed spin-1/2 and spin-S (S>1/2) Ising model on a decorated square lattice is thoroughly examined in presence of the transverse magnetic field within the generalized decoration-iteration transformation, which provides an exact mapping relation with an effective spin-1/2 Ising model on a square lattice in a zero magnetic field. Temperature dependencies of the entropy and isothermal entropy change exhibit an outstanding singular behavior in a close neighborhood of temperature-driven continuous phase transitions, which can be additionally tuned by the applied transverse magnetic field. While temperature variations of the entropy display in proximity of the critical temperature Tc a striking energy-type singularity (T−Tc)log|T−Tc|, two analogous weak singularities can be encountered in the temperature dependence of the isothermal entropy change. The basic magnetocaloric measurement of the isothermal entropy change may accordingly afford the smoking gun evidence of continuous phase transitions. It is shown that the investigated model predominantly displays the conventional magnetocaloric effect with exception of a small range of moderate temperatures, which contrarily promotes the inverse magnetocaloric effect. It turns out that the temperature range inherent to the inverse magnetocaloric effect is gradually suppressed upon increasing of the spin magnitude S.

ISING MODEL ON A LAYERED SQUARE LATTICE

1989 ◽  
Vol 03 (07) ◽  
pp. 1119-1128
Author(s):  
K.Y. LIN ◽  
K.J. HSU
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
Ising Model ◽  
Transfer Matrix ◽  
Square Lattice ◽  
The Magnetic Field

We have considered the Ising model on a layered square lattice where each layer has a different set of horizontal and vertical interactions. The free energy is determined exactly by the method of Pfaffian at two values of the magnetic field, H=0 and H=iπkT/2. The free energy at H=0 was first derived by Wolff et al. using the method of transfer matrix.

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