scholarly journals Universal scaling of Néel temperature, staggered magnetization density, and spin-wave velocity of three-dimensional disordered and clean quantum antiferromagnets

2017 ◽  
Vol 95 (5) ◽  
Author(s):  
D.-R. Tan ◽  
F.-J. Jiang
Keyword(s):  
Spin Wave ◽  
Wave Velocity ◽  
Three Dimensional ◽  
Neel Temperature ◽  
Néel Temperature ◽  
Universal Scaling ◽  
Quantum Antiferromagnets ◽  
Magnetization Density

THEORETICAL MODELS FOR MAGNETIC PROPERTIES OF IRON PNICTIDES

2013 ◽  
Vol 27 (16) ◽  
pp. 1350071 ◽  
Author(s):  
M. VUJINOVIĆ ◽  
M. PANTIĆ ◽  
D. KAPOR ◽  
P. MALI
Keyword(s):  
Magnetic Properties ◽  
Heisenberg Model ◽  
Degrees Of Freedom ◽  
Random Phase ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Wave Dispersion ◽  
Model Parameters ◽  
Neel Temperature ◽  
Néel Temperature

We attempt to describe the magnetic properties of parent pnictide compounds by using both the J1–J2 Heisenberg model and its three-dimensional generalization, the J1–J2–Jc model. We also include spin anisotropy in the XY plane. In order to obtain the average magnetization and spin wave dispersion, we use the Green's functions method for spin operators in the random phase approximation. We obtain estimates for the model parameters by considering the low temperature experimental dispersion for the compounds CaFe 2 As 2 and BaFe 2 As 2 and conclude that theoretical dispersion can fit the experimental one if spatially anisotropic Hamiltonian is used. A good agreement between theory and experiment indicates that the Heisenberg model is applicable to parent pnictides at low temperatures. The applicability of the model for higher temperatures is checked by calculating the Néel temperature for both compounds. It turns out that the model overestimates the measured critical temperature. The Heisenberg model is not applicable to parent pnictides, for temperature comparable to Néel temperature. Our results thus confirm that all the magnetic properties of parent pnictides cannot be described with purely localized degrees of freedom, and that the itinerant magnetism should have an important role in these compounds. All results given in Sec. 3 are general and could be used in description of classes of compounds with spin stripe structure.

On the Green function theory of a Heisenberg antiferromagnet

1968 ◽  
Vol 46 (12) ◽  
pp. 1435-1442 ◽  
Author(s):  
S. T. Dembinski
Keyword(s):  
Green Function ◽  
Low Temperature ◽  
Curie Temperature ◽  
Spin Wave ◽  
Function Theory ◽  
Neel Temperature ◽  
Heisenberg Antiferromagnet ◽  
Néel Temperature ◽  
First Order ◽  
The Green Function

Some of the consequences of a recently proposed first-order decoupling are examined in the Green function theory of a [Formula: see text] Heisenberg antiferromagnet. The low-temperature magnetization differs in terms proportional to T4 from Oguchi's spin wave formula. The Neél temperature is equal to the R.P.A, Curie temperature.

scholarly journals Néel Temperature of Antiferromagnets for Phase Transitions Driven by Spin-wave Interactions

2013 ◽  
Vol 86 (4) ◽  
pp. 463-467 ◽  
Author(s):  
Andrés Ayuela ◽  
Douglas J. Klein ◽  
Norman H. March
Keyword(s):  
Phase Transitions ◽  
Spin Wave ◽  
Neel Temperature ◽  
Néel Temperature ◽  
Wave Interactions
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