scholarly journals Quantum dynamics of the square-lattice Heisenberg model

2018 ◽  
Vol 98 (15) ◽  
Author(s):  
Ruben Verresen ◽  
Frank Pollmann ◽  
Roderich Moessner
Keyword(s):  
Heisenberg Model ◽  
Quantum Dynamics ◽  
Square Lattice

scholarly journals Finite temperature properties and frustrated ferromagnetism in a square lattice Heisenberg model

2004 ◽  
Vol 38 (4) ◽  
pp. 599-616 ◽  
Author(s):  
N. Shannon ◽  
B. Schmidt ◽  
K. Penc ◽  
P. Thalmeier
Keyword(s):  
Finite Temperature ◽  
Heisenberg Model ◽  
Square Lattice

THE DISAPPEARANCE OF TWO-DIMENSIONAL LONG RANGE ORDER IN THE HEISENBERG MODEL WITH COMPETING INTERACTIONS

1990 ◽  
Vol 04 (15n16) ◽  
pp. 2319-2333 ◽  
Author(s):  
A. F. BARABANOV ◽  
L. A. MAKSIMOV ◽  
O. A. STARYKH
Keyword(s):  
Long Range ◽  
Heisenberg Model ◽  
Spin Correlation ◽  
Range Order ◽  
Square Lattice ◽  
Spin Excitation ◽  
Spin Liquid ◽  
Long Range Order ◽  
Competing Interactions ◽  
Nearest Neighbours

In the frustrated Heisenberg model with first (J1) and second (J2) nearest neighbours interactions on a square lattice the transition from the long range order state (LROS) to spin liquid state (SLS) is found at α = J1/J2 ≅ 0.25. SLS is characterized by the gap in spin excitation spectrum at T = 0 and, hence, by exponential decay of spin correlation function at large distance. As a result, correlation length is temperature independent in SLS in accordance with neutron experiments on doped La 2 CuO 4.

Thermodynamic Properties of an In-Phase Flux Antiferromagnetic Spin Coupled Heisenberg Model on a Square Lattice

SPIN ◽  
2018 ◽  
Vol 08 (04) ◽  
pp. 1830001
Author(s):  
E. Mainimo ◽  
N. Ibrahim Famenyi
Keyword(s):  
Energy Spectrum ◽  
Specific Heat ◽  
Thermodynamic Parameters ◽  
Heisenberg Model ◽  
State Energy ◽  
Spontaneous Magnetization ◽  
Exchange Interactions ◽  
Spin Model ◽  
Square Lattice ◽  
Antiferromagnetic Spin

Using the two-dimensional Jordan–Wigner Fermionization procedure, we calculate the energy spectrum of the in-phase flux antiferromagnetically spin-1/2 coupled Heisenberg model in a square lattice, the formalism used introduces the notion of isotropic parameters. The energy spectrum is analyzed for various regimes of the exchange interactions and the isotropic parameters. The thermodynamic parameters of the lattice, notably the ground state energy, the free energy, mean energy, entropy and specific heat are calculated. It is seen that the specific heat undergoes a phase transition at a temperature below the critical temperature due to spontaneous magnetization. Its entropy for homogeneous and completely isotropic regime is compared for two regimes of the exchange interaction and it is observed that the entropy decreases with an increase in the coupling strength. All the thermodynamic parameters calculated for this spin model are seen to be in conformity with the principles and laws of Statistical Thermodynamics.

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