Hirschfeld surface analysis and short-range ferromagnetic ordering in La0.5Ca0.4Ag0.1MnO3 based on critical behavior study

2018 ◽  
Author(s):  
Mourad Smari
Keyword(s):  
Surface Analysis ◽  
Critical Exponents ◽  
Short Range ◽  
Magnetic Measurements ◽  
Spontaneous Magnetization ◽  
Mean Field ◽  
Ferromagnetic Phase ◽  
Behavior Study ◽  
Critical Model ◽  
Ferromagnetic Ordering

We investigated the Hirschfeld surface analysis and critical behaviour in La0.5Ca0.4Ag0.1MnO3 near the second-order ferromagnetic phase transition at Curie temperature TC. We determined the critical exponents, β, γ and δ corresponding to the temperature dependence of spontaneous magnetization, initial susceptibility and isothermal magnetization, respectively. The study of Hirshfeld surface reflects that both the electrostatic and intermolecular interactions are short range. The values for critical exponents obtained from magnetic measurements are very close to those predicted by the mean field tri-critical model.  The critical-exponent values deduced here were in a good conform to those obtained using the modified Arrott plot and Widom scaling relation.

TWO-DIMENSIONAL FERROMAGNETIC ORDERING IN A METAL–ORGANIC MULTILAYER STRUCTURE

2005 ◽  
Vol 04 (05n06) ◽  
pp. 831-837 ◽  
Author(s):  
M. K. SANYAL ◽  
M. K. MUKHOPADHYAY ◽  
R. M. DALGLIESH ◽  
S. LANGRIDGE
Keyword(s):  
Magnetic Measurements ◽  
Spontaneous Magnetization ◽  
Spin Fluctuations ◽  
Neutron Reflectivity ◽  
Two Dimensional ◽  
Crystalline Anisotropy ◽  
Theoretical Predictions ◽  
Metal Organic ◽  
Plane Direction ◽  
Ferromagnetic Ordering

We demonstrate, using spin polarized neutron reflectivity measurements, that one can form a large stack of magnetically decoupled spin-membranes of Gadolinium ions and reduce the effect of the substrate substantially to study short-range two-dimensional (2D) ferromagnetic ordering. No spontaneous magnetization was observed in these membranes as the magnetic field was applied along an in-plane direction. The results are consistent with theoretical predictions of 2D in-plane spin systems having strong interplay of exchange, magneto-crystalline anisotropy and dipolar interactions. These metal–organic multilayer films will enable us to verify various theoretical predictions regarding spin-fluctuations in 2D systems using conventional magnetic measurements and neutron scattering studies.

Estimating spontaneous magnetization from mean field analysis and critical exponents study in La0.6Sr0.4Mn0.9Al0.1O3 compound

2018 ◽  
Vol 460 ◽  
pp. 480-488 ◽  
Author(s):  
Amal Elhamza ◽  
S.E.L. Kossi ◽  
J. Dhahri ◽  
E.K. Hlil ◽  
M.A. Zaidi ◽  
...  
Keyword(s):  
Critical Exponents ◽  
Spontaneous Magnetization ◽  
Mean Field ◽  
Field Analysis

scholarly journals Finite-temperature critical behavior of long-range quantum Ising models

2021 ◽  
Vol 11 (4) ◽  
Author(s):  
Eduardo Gonzalez Lazo ◽  
Markus Heyl ◽  
Marcello Dalmonte ◽  
Adriano Angelone
Keyword(s):  
Long Range ◽  
Critical Exponents ◽  
Ground State ◽  
Large Scale ◽  
Mean Field ◽  
Universality Class ◽  
Ising Models ◽  
Ferromagnetic Phase ◽  
Nonzero Temperature ◽  
Mean Field Limit

We study the phase diagram and critical properties of quantum Ising chains with long-range ferromagnetic interactions decaying in a power-law fashion with exponent \alphaα, in regimes of direct interest for current trapped ion experiments. Using large-scale path integral Monte Carlo simulations, we investigate both the ground-state and the nonzero-temperature regimes. We identify the phase boundary of the ferromagnetic phase and obtain accurate estimates for the ferromagnetic-paramagnetic transition temperatures. We further determine the critical exponents of the respective transitions. Our results are in agreement with existing predictions for interaction exponents \alpha<1α>1 up to small deviations in some critical exponents. We also address the elusive regime \alpha < 1α<1, where we find that the universality class of both the ground-state and nonzero-temperature transition is consistent with the mean-field limit at \alpha = 0α=0. Our work not only contributes to the understanding of the equilibrium properties of long-range interacting quantum Ising models, but can also be important for addressing fundamental dynamical aspects, such as issues concerning the open question of thermalization in such models.

Nonclassical critical exponents out of mean-field results

1998 ◽  
Vol 260 (1-2) ◽  
pp. 99-105 ◽  
Author(s):  
Tânia Tomé ◽  
Mário J.de Oliveira
Keyword(s):  
Critical Exponents ◽  
Mean Field

Landau mean-field analysis of magnetic entropy change and spontaneous magnetization estimation in Nd0.6Sr0.3K0.1MnO3 perovskite

2021 ◽  
Vol 127 (12) ◽  
Author(s):  
M. Jeddi ◽  
J. Massoudi ◽  
H. Gharsallah ◽  
Sameh I. Ahmed ◽  
E. Dhahri ◽  
...  
Keyword(s):  
Magnetic Entropy Change ◽  
Spontaneous Magnetization ◽  
Mean Field ◽  
Entropy Change ◽  
Field Analysis ◽  
Magnetic Entropy

scholarly journals Equivalent-neighbor percolation models in two dimensions: Crossover between mean-field and short-range behavior

2018 ◽  
Vol 98 (6) ◽  
Author(s):  
Yunqing Ouyang ◽  
Youjin Deng ◽  
Henk W. J. Blöte
Keyword(s):  
Short Range ◽  
Mean Field ◽  
Two Dimensions

scholarly journals Population dynamics with spatial structure and an Allee effect

2020 ◽  
Author(s):  
Anudeep Surendran ◽  
Michael Plank ◽  
Matthew Simpson
Keyword(s):  
Population Dynamics ◽  
Spatial Structure ◽  
Short Range ◽  
Allee Effect ◽  
Mean Field ◽  
Mean Field Approximation ◽  
Continuum Approximation ◽  
Spatial Moment ◽  
Mean Field Models ◽  
The Mean

AbstractAllee effects describe populations in which long-term survival is only possible if the population density is above some threshold level. A simple mathematical model of an Allee effect is one where initial densities below the threshold lead to population extinction, whereas initial densities above the threshold eventually asymptote to some positive carrying capacity density. Mean field models of population dynamics neglect spatial structure that can arise through short-range interactions, such as short-range competition and dispersal. The influence of such non mean-field effects has not been studied in the presence of an Allee effect. To address this we develop an individual-based model (IBM) that incorporates both short-range interactions and an Allee effect. To explore the role of spatial structure we derive a mathematically tractable continuum approximation of the IBM in terms of the dynamics of spatial moments. In the limit of long-range interactions where the mean-field approximation holds, our modelling framework accurately recovers the mean-field Allee threshold. We show that the Allee threshold is sensitive to spatial structure that mean-field models neglect. For example, we show that there are cases where the mean-field model predicts extinction but the population actually survives and vice versa. Through simulations we show that our new spatial moment dynamics model accurately captures the modified Allee threshold in the presence of spatial structure.

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