scholarly journals Correlation magnetodynamics equations for antiferro- and ferrimagnets

2021 ◽  
pp. 1-13
Author(s):  
Anton Valerievich Ivanov
Keyword(s):  
Distribution Function ◽  
Particle Distribution ◽  
Particle Distribution Function ◽  
System Of Equations ◽  
Main Difficulty ◽  
Crystal Lattices ◽  
Pairwise Correlations ◽  
Face Centered ◽  
Bogolyubov Chain ◽  
New System

Based on the Bogolyubov chain and a new approximation of the two-particle distribution function a new system of equations of correlation magnetodynamics is obtained for antiferro- and ferrimagnets. Body-centered and face-centered crystal lattices are considered. The system contains one world-magnetic equation of the Landau-Lifshitz-Bloch type for each sublattice and several equations for pairwise correlations between sublattices. In this case, the main difficulty is the calculation of the integral coefficients of the resulting system of equations.

scholarly journals Correlation magnetodynamics equations taking into account the uniaxial quadratic correction in the approximation of the one-particle distribution function

2021 ◽  
pp. 1-16
Author(s):  
Anton Valerievich Ivanov
Keyword(s):  
Distribution Function ◽  
Particle Distribution ◽  
Nearest Neighbors ◽  
Particle Distribution Function ◽  
Phase Transition Region ◽  
Simulation Results ◽  
The One ◽  
Bogolyubov Chain ◽  
New System ◽  
Good Agreement

The system of equations for correlation magnetodynamics (CMD) is based on the Bogolyubov chain and approximation of the two-particle distribution function taking into account the correlations between the nearest neighbors. CMD provides good agreement with atom-for-atom simulation results (which are considered ab initio), but there is some discrepancy in the phase transition region. To solve this problem, a new system of CMD equations is constructed, which takes into account the quadratic correction in the approximation of the one-particle distribution function. The system can be simplified in a uniaxial case.

scholarly journals Approximation of many-particle distribution functions for ferromagnetics with different crystal lattices

2021 ◽  
pp. 1-22
Author(s):  
Anton Valerievich Ivanov
Keyword(s):  
Particle Distribution ◽  
Nearest Neighbors ◽  
Bbgky Hierarchy ◽  
Distribution Functions ◽  
Atomistic Simulations ◽  
System Of Equations ◽  
Crystal Lattices ◽  
Face Centered ◽  
The Many ◽  
New System

We propose the new system of equations for magnetodynamics. Thus we call the new system of equations correlational magnetodynamics system (CMD). It consists of well known Landau–Lifshitz–Bloch(LLB) equation complemented with an equation for two-particles correlations. It is based on BBGKY hierarchy, the key issue is the approximation of the many-particle distribution functions taking into account the correlations between the nearest neighbors for different (primitive, body-centered and face-centered) crystal lattices. Compared to traditional LLB equation, numerical simulations with CMD produces results that are closer to atomistic simulations.

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