scholarly journals Anisotropic Heisenberg model for the mixed spin-3/2 and spin-1/2 under random crystal field

2021 ◽  
Vol 24 (1) ◽  
pp. 13704
Author(s):  
D. Sabi Takou ◽  
M. Karimou ◽  
F. Hontinfinde ◽  
E. Albayrak
Keyword(s):  
Crystal Field ◽  
Heisenberg Model ◽  
Classical Case ◽  
Absolute Temperature ◽  
Quantum Model ◽  
Mixed Spin ◽  
Wide Range ◽  
Classical Quantum ◽  
Oguchi Approximation ◽  
Qualitative Changes

Thermodynamic properties of the mixed spin-3/2 and spin-1/2 Heisenberg model are examined within the Oguchi approximation in the presence of a random crystal-field (RCF). The RCF is either introduced with probability p or turned off with probability 1-p randomly. The thermal variations of the global magnetization and free energy of the system are investigated to construct the phase diagrams for the classical, quantum and anisotropic cases. Different results revealed that no qualitative changes exist between them. Quantum effects are found to be present and abundant in the quantum model in the negative D -range. This phenomenon has a strong decreasing effect on the critical temperature which becomes much lower than in the classical case. In the presence of an external field, it was observed that coercivity and remanence decrease in a wide range of the absolute temperature.

scholarly journals Monte Carlo study of the anisotropic three-dimensional Heisenberg model in a crystal field

2004 ◽  
Vol 34 (2a) ◽  
pp. 452-454 ◽  
Author(s):  
R. T. S. Freire ◽  
J. A. Plascak ◽  
B. V. da Costa
Keyword(s):  
Monte Carlo ◽  
Crystal Field ◽  
Heisenberg Model ◽  
Three Dimensional ◽  
Monte Carlo Study

Random Crystal Field in a Mixed Spin S =  1/2 and S =  3/2 Ising Model by Renormalization Group Theory

2018 ◽  
Vol 31 (12) ◽  
pp. 3949-3957 ◽  
Author(s):  
S. Zouhair ◽  
M. Monkade ◽  
M. Bourass ◽  
A. El Antari ◽  
M. El Bouziani ◽  
...  
Keyword(s):  
Renormalization Group ◽  
Group Theory ◽  
Ising Model ◽  
Crystal Field ◽  
Renormalization Group Theory ◽  
Mixed Spin

Testate amoebae as non-pollen palynomorphs in pollen slides: Usefulness and application in palaeoenvironmental reconstruction

2020 ◽  
pp. SP511-2020-34
Author(s):  
L. O. Andrews ◽  
R. J. Payne ◽  
G. T. Swindles
Keyword(s):  
Water Table ◽  
Transfer Functions ◽  
Testate Amoebae ◽  
Water Table Depth ◽  
Qualitative Assessment ◽  
Distribution Data ◽  
Preparation Methods ◽  
Chemical Treatments ◽  
Wide Range ◽  
Qualitative Changes

AbstractTestate amoebae are a frequently used palaeoecological proxy for reconstructing changes in palaeohydrological conditions, particularly in studies of Sphagnum-dominated peatlands. Their use in palaeoecological studies has increased following the development of transfer functions, allowing for the quantitative reconstruction of water-table depth changes through time. Increasingly, they are included in non-pollen palynomorph (NPP) studies alongside a wide range of other proxies, representing a valuable tool, particularly in multi-proxy studies.Testate amoebae have been used for qualitative assessment of palaeohydrology in NPP studies and may aid the verification of environmental interpretations of conditions inferred from curves of NPP with unknown ecology and taxonomy. Their usefulness in such studies is limited by the destruction of tests owing to harsh chemical treatments used in pollen preparation methods. This makes community distribution data of testate amoebae derived by these methods largely unsuitable for quantitative assessment of water-table depth. Furthermore, many palynological studies combine testate amoebae as one single curve, losing further ecological detail. Patterns of change of surviving species, most commonly of Assulina, Archerella, Arcella, Hyalosphenia and Archerella flavum, remain relatively unaffected and therefore can still be useful for interpreting qualitative changes in hydrological conditions through time, particularly when coupled with other proxies.

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