Effective-Field Approach to Magnetic Properties of Spin-1 System in XXZ Model with Single-Ion Uniaxial Anisotropy

2020 ◽  
Vol 89 (3) ◽  
pp. 034002
Author(s):  
Masashige Onoda ◽  
Satoshi Takada
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Igor N. Karnaukhov

AbstractUsing mean field approach, we provide analytical and numerical solution of the symmetric Anderson lattice for arbitrary dimension at half filling. The symmetric Anderson lattice is equivalent to the Kondo lattice, which makes it possible to study the behavior of an electron liquid in the Kondo lattice. We have shown that, due to hybridization (through an effective field due to localized electrons) of electrons with different spins and momenta $$\mathbf{k} $$ k and $$\mathbf{k} +\overrightarrow{\pi }$$ k + π → , the gap in the electron spectrum opens at half filling. Such hybridization breaks the conservation of the total magnetic momentum of electrons, the spontaneous symmetry is broken. The state of electron liquid is characterized by a large Fermi surface. A gap in the spectrum is calculated depending on the magnitude of the on-site Coulomb repulsion and value of s–d hybridization for the chain, as well as for square and cubic lattices. Anomalous behavior of the heat capacity at low temperatures in the gapped state, which is realized in the symmetric Anderson lattice, was also found.


1994 ◽  
Vol 76 (10) ◽  
pp. 6986-6988 ◽  
Author(s):  
T. Yeh ◽  
L. Berg ◽  
B. Witcraft ◽  
J. Falenschek ◽  
J. Yue

2012 ◽  
Vol 02 (02) ◽  
pp. 1241007 ◽  
Author(s):  
C. L. WANG ◽  
C. ARAGÓ ◽  
M. I. MARQUÉS

The explicit expression of Helmholtz free energy has been obtained from the equation of state from effective field approach. From the Helmholtz free energy, four characteristic temperatures describing a first-order ferroelectric phase transitions have been determined. The physical meaning of coefficients in Landau-type free energy has been revealed by comparison with the expanding Helmholtz function. Temperature dependence of polarization under different bias, and hysteresis loops at different temperatures are presented and discussed. These results provide the basic understandings of the static properties of first-order ferroelectric phase transitions.


2018 ◽  
Vol 24 (3) ◽  
pp. 778-795 ◽  
Author(s):  
Milan Mićunović ◽  
Ljudmila Kudrjavceva

This paper deals with a body that has a random 3D-distribution of two phase inclusions: spheroidal mutually parallel voids, and differently oriented reinforcing parallel stiff spheroidal short fibers. By the effective field approach the effective stiffness fourth order tensor is formulated and found numerically. Simultaneous and sequential embeddings of inclusions are compared. Damage evolution is described by a modified Vakulenko approach to the endochronic thermodynamics. A brief account of the problem of effective elastic symmetry is considered. The results of the theory are applied to the damage-elasto-viscoplastic strain of a reactor stainless steel AISI 316H.


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