Single-particle Green's function in an anisotropic Heisenberg model

1973 ◽  
Vol 14 (1) ◽  
pp. 75-89 ◽  
Author(s):  
Yu. G. Rudoi ◽  
Yu. A. Tserkovnikov
2002 ◽  
Vol 16 (25) ◽  
pp. 3803-3816 ◽  
Author(s):  
HUAI-YU WANG ◽  
KE-QIU CHEN ◽  
EN-GE WANG

The fermionic Green's function theory of Heisenberg-like Hamiltonian is presented in this paper. For the case that the Hamiltonian is isotropic and the higher-order Green's function is asymmetrically decoupled, the present theory is equivalent to the bosonic Green's function theory. When the Hamiltonian is anisotropic and the higher-order Green's function is symmetrically decoupled, it gives the universal formula to calculate the three components of statistical average of spin operators which one encountered when dealing with ferromagnetic or ferroelectric systems described by anisotropic Heisenberg model or pseudospin model respectively. Both cases of <Sz> ≠ 0 and <Sz> = 0 are investigated. Explicit expressions are derived for spin value S = 1/2, 1, 3/2, 2, and 5/2. General expressions for any S value are suggested.


2021 ◽  
Vol 104 (8) ◽  
Author(s):  
Dominik Lessnich ◽  
Stephen M. Winter ◽  
Mikel Iraola ◽  
Maia G. Vergniory ◽  
Roser Valentí

2020 ◽  
Vol 44 (8) ◽  
pp. 084105
Author(s):  
Cheng Chen ◽  
Zhipan Li ◽  
Yuxiao Li ◽  
Tingting Sun

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