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| 11. |
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| 12. |
- Attia, Zachi I., et al.
(author)
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Rapid Exclusion of COVID Infection With the Artificial Intelligence Electrocardiogram
- 2021
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In: Mayo Clinic proceedings. - : ELSEVIER SCIENCE INC. - 0025-6196 .- 1942-5546. ; 96:8, s. 2081-2094
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Journal article (peer-reviewed)abstract
- Objective: To rapidly exclude severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection using artificial intelligence applied to the electrocardiogram (ECG). Methods: A global, volunteer consortium from 4 continents identified patients with ECGs obtained around the time of polymerase chain reaction-confirmed COVID-19 diagnosis and age- and sex-matched controls from the same sites. Clinical characteristics, polymerase chain reaction results, and raw electrocardiographic data were collected. A convolutional neural network was trained using 26,153 ECGs (33.2% COVID positive), validated with 3826 ECGs (33.3% positive), and tested on 7870 ECGs not included in other sets (32.7% positive). Performance under different prevalence values was tested by adding control ECGs from a single high-volume site. Results: The area under the curve for detection of acute COVID-19 infection in the test group was 0.767 (95% CI, 0.756 to 0.778; sensitivity, 98%; specificity, 10%; positive predictive value, 37%; negative predictive value, 91%). To more accurately reflect a real-world population, 50,905 normal controls were added to adjust the COVID prevalence to approximately 5% (2657/58,555), resulting in an area under the curve of 0.780 (95% CI, 0.771 to 0.790) with a specificity of 12.1% and a negative predictive value of 99.2%. Conclusion: Infection with SARS-CoV-2 results in electrocardiographic changes that permit the artificial intelligence-enhanced ECG to be used as a rapid screening test with a high negative predictive value (99.2%). This may permit the development of electrocardiography-based tools to rapidly screen individuals for pandemic control. (C) 2021 Mayo Foundation Medical Education and Research
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| 13. |
- Benhouria, Y., et al.
(author)
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Dielectric Properties and Hysteresis Loops of a Ferroelectric Nanoparticle System Described by the Transverse Ising Model
- 2014
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In: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 27:9, s. 2153-2162
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Journal article (peer-reviewed)abstract
- In this work, we use the effective field theory based on the probability distribution method to investigate the longitudinal and transverse polarizations, susceptibility, pyroelectric coefficient, and the hysteresis behavior of a ferroelectric cubic nanowire. The effects of the core-shell exchange interaction and the core-shell transverse fields on the longitudinal and transverse polarizations, the susceptibility, the pyroelectric coefficient, and the hysteresis loops of the system are examined. Some characteristic phenomena are found in the thermal variations, depending on the physical parameters in the shell and in the core.
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| 14. |
- Benhouria, Y., et al.
(author)
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Hysteresis loops and dielectric properties of a mixed spin Blume-Capel Ising ferroelectric nanowire
- 2018
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In: Physica A. - : ELSEVIER SCIENCE BV. - 0378-4371 .- 1873-2119. ; 506, s. 499-506
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Journal article (peer-reviewed)abstract
- The critical and hysteresis behaviors of a ferrielectric Blume-Capel nanowire are studied using the 'sing model with mixed spins -(1/2,1) in the presence of both an external longitudinal electric (E-z) and crystal anisotropy (D) fields. We use the Monte Carlo simulations (MCs) to examine the influence of E-z, D and the exchange interactions on the compensation and critical temperatures, the specific heat, the dielectric susceptibility and the internal energy of the system. Our theoretical predictions are in accordance with some experimental and theoretical results.
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| 15. |
- Benhouria, Y., et al.
(author)
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Hysteresis loops and dielectric properties of compositionally graded (Ba,Sr)TiO3 thin films described by the transverse Ising model
- 2016
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In: Zhongguó wùli xuékan. - : Elsevier BV. - 0577-9073. ; 54:4, s. 533-544
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Journal article (peer-reviewed)abstract
- Using the effective field theory with a probability distribution technique that accounts for the self-spin correlations, we apply the transverse spin-1/2 Ising model to study the intrinsic hysteresis of compositionally graded Ba1-xSrxTiO3 (BST) thin films with x decreasing from 0.20 to 0.10 in successive slabs. The random bond model of related parameters is applied to mimic doping. The effects of the thickness, the concentration of Sr, the number of slabs and the temperature on the polarization and the hysteresis are discussed.
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| 16. |
- Benhouria, Y., et al.
(author)
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Monte Carlo simulation of dielectric properties of a mixed spin-3/2 and spin-5/2 Ising ferrielectric nanowires
- 2017
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In: Ferroelectrics (Print). - : TAYLOR & FRANCIS LTD. - 0015-0193 .- 1563-5112. ; 507:1, s. 58-68
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Journal article (peer-reviewed)abstract
- Dielectric properties of Ising ferrielectric nanowires with spin-3/2 core and spin-5/2 shell structure are systematically studied by the use of the Monte Carlo simulation in the presence of the external longitudinal electric field. Special focus is given to the effects of the core and shell interactions, the interface coupling and the temperature on the core and shell polarizations, the specific heat, the compensations points, the susceptibility and hysteresis behaviors. Some characteristic behaviors are found, such as the existence of triple hysteresis loops for appropriate values of the system parameters affected by the antiferroelectric interface coupling constant and the temperature. The results are compared with those of recently published works and a qualitatively good agreement is found.
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| 17. |
- Benhouria, Y., et al.
(author)
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Monte Carlo Study of Long-Range Interactions of a Ferroelectric Bilayer with Antiferroelectric Interfacial Coupling
- 2013
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In: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 26:10, s. 3075-3083
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Journal article (peer-reviewed)abstract
- By the use of Monte Carlo simulation, we have studied the critical behavior of a ferroelectric bilayer with antiferroelectric interfacial coupling using the transverse spin- Ising model. We discuss the effects of long-range interactions for the internal energy, specific heat, free energy, dielectric susceptibility, and polarization. The dependence of the Curie temperature on the thickness of the bilayer, long-range interactions, and the transverse field was also investigated. It is assumed that the long-range interaction decays with the distance between the pseudo-spins as a power law.
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| 18. |
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| 19. |
- Benhouria, Y., et al.
(author)
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Thermodynamic properties and hysteresis behaviors of a mixed spin-3/2 and spin-1/2 Ising double walled ferrielectric nanotubes : A Monte Carlo study
- 2014
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In: Superlattices and Microstructures. - : Elsevier BV. - 0749-6036 .- 1096-3677. ; 75, s. 761-774
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Journal article (peer-reviewed)abstract
- The hysteresis loops and the thermodynamic properties of a ferroelectric or ferrielectric double walled nanotubes (A and B) are studied within the Ising model with mixed spins (S-A = 3/2 and S-B = 1/2) in the presence of the crystal and the external longitudinal electric fields. We use the Monte Carlo method to investigate the effects of the external electric field, the crystal field and the exchange interactions on the total polarization, susceptibility, specific heat and the internal energy of a double walled nanotubes (DWNTs).
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| 20. |
- Bouhou, S., et al.
(author)
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Magnetic Properties of a Transverse Ising Nanoparticle
- 2015
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In: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 28:3, s. 885-890
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Journal article (peer-reviewed)abstract
- We use the effective field theory with a probability distribution technique to investigate the magnetic properties of an antiferromagnetic Ising core/shell nanoparticle with a negative interlayer coupling core/shell in the presence of both the longitudinal and the transverse fields. Nearest-neighbor pair interactions are incorporated between the Ising spins in three parts that are core, core/shell, and surface shell. The effects of the external and the transverse fields and the exchange interactions between core/shell and in surface shell on the hysteresis loops and the susceptibility of the nanoparticle are examined. A number of interesting phenomena have been found.
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| 21. |
- Bouhou, S., et al.
(author)
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Magnetic Properties of Diluted Magnetic Nanowire
- 2013
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In: J SUPERCOND NOV MAGN. - : Springer Science and Business Media LLC. - 1557-1939. ; 26:1, s. 201-211
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Journal article (peer-reviewed)abstract
- A magnetic diluted nanowire with cylindrical structure described by the Ising model is investigated. Using the effective field theory with a probability distribution technique, the influence of the dilution on the phase diagrams, susceptibility and the hysteresis loops are discussed in detail. Novel features are obtained for the thermal variations of longitudinal susceptibility and longitudinal magnetization. We have investigated the magnetic reversal of the system and have found the existence of triple hysteresis loops patterns, affected by the concentration of magnetic atoms, the temperature, and the exchange interaction between the core and the surface shell.
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| 22. |
- Bouhou, S., et al.
(author)
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Phase diagrams of diluted transverse Ising nanowire
- 2013
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In: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 336, s. 75-82
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Journal article (peer-reviewed)abstract
- In this paper, the phase diagrams of diluted Ising nanowire consisting of core and surface shell coupling by J(cs) exchange interaction are studied using the effective field theory with a probability distribution technique, in the presence of transverse fields in the core and in the surface shell. We find a number of characteristic phenomena. In particular, the effect of concentration c of magnetic atoms, the exchange interaction core/shell, the exchange in surface and the transverse fields in core and in surface shell of phase diagrams are investigated.
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| 23. |
- Bouhou, S., et al.
(author)
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Some hysteresis loop features of 2D magnetic spin-1 Ising nanoparticle : shape lattice and single-ion anisotropy effects
- 2017
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In: Zhongguó wùli xuékan. - : Elsevier BV. - 0577-9073. ; 55:6, s. 2224-2235
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Journal article (peer-reviewed)abstract
- The effects of longitudinal and transverse crystal-fields on the magnetic hysteresis behaviors of 2D spin-1 Ising nanoparticles are investigated, by using the effective-field theory based on the probability distribution technique with correlations. Nanoparticles with hexagonal or square lattice are studied. A number of characteristic phenomena such as triple and quadruple hysteresis loop behaviors have been observed for certain physical parameters, originating from the competitions among the core/shell exchange interaction, anisotropies, temperature and the longitudinal magnetic field. Finally, the obtained results are compared with some experimental and theoretical results.
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| 24. |
- Chafai, A., et al.
(author)
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Binding energy of an exciton in a GaN/AlN nanodot : Role of size and external electric field
- 2019
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In: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 559, s. 23-28
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Journal article (peer-reviewed)abstract
- We report the impact of an external electric field on the energy spectrum of an exciton inside a spherical shaped GaN/AlN core/shell nanodot. The modulation of the confined exciton lowest state energy by the nanodot size is also treated. Our theoretical approach, based on a variational calculation, predicts a remarkable decrease in the exciton's energy when the electric field is switched on. Furthermore, our investigation shows that for a fixed nanodot size, the energy redshift is a unique function of the external electric field strength. On the other hand, it was observed that as the nanodot size increases the lowest exciton energy decreases and vice versa.
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| 25. |
- Chafai, A., et al.
(author)
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Hydrogenic donor in a CdSe/CdS quantum dot : Effect of electric field strength, nanodot shape and dielectric environment on the energy spectrum
- 2018
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In: Physica. E, Low-Dimensional systems and nanostructures. - : Elsevier BV. - 1386-9477 .- 1873-1759. ; 104, s. 29-35
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Journal article (peer-reviewed)abstract
- The impact of an external electric field on the binding energy of a single donor impurity was examined within the effective-mass approach by deploying a variational calculation. The discontinuity of the permittivity, epsilon(r), and of the particle effective mass, m(i)*(r), at the nanosystem boundaries was considered. Using the image charge approach, the impact of the surrounding medium on the shallow donor energy spectrum was also taken into account. Our theoretical investigation shows that, for zero electric field and when the shell thickness is taken constant, the increase of the core material size leads to decrease the single donor correlation energy. Further, for a fixed core material size the energy decreases quickly when the shell thickness moves from 0 to 1 nm, while it decreases very slowly when the shell thickness is ranged between 1 nm and 4 nm. On the other hand, we have established that when we turn on an external electric field, the probability density of confined particles tends to move towards the nanodot border which naturally shifts the energy spectrum to lower energies (redshift). It was also obtained that the donor Stark shift depends not only on the nanodot size, but also on the surrounding medium.
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| 26. |
- Chafai, A., et al.
(author)
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Recombination energy for negatively charged excitons inside type-II core/shell spherical quantum dots
- 2018
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In: Physica. E, Low-Dimensional systems and nanostructures. - : ELSEVIER SCIENCE BV. - 1386-9477 .- 1873-1759. ; 101, s. 125-130
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Journal article (peer-reviewed)abstract
- The recombination energy of isolated neutral exciton and that of isolated negatively charged exciton inside a type-II core/shell spherical quantum dot are studied. Our investigation considers the charge-carriers effective mass discontinuity at the surface contact between the core and shell materials. Although our model omits the effect of the surface polarization, the dielectric-constant mismatch at the nanodot boundaries was taken into account. In order to achieve the exciton and negative trion energies, we proceed by a variational calculation in the framework of the envelope approximation. Our results reveal a strong correlation between the nanodot morphology and the energy spectrum of the neutral and negatively charged exciton.
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| 27. |
- Chafai, A., et al.
(author)
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Role of a uniform magnetic field on the energy spectrum of a single donor in a core/shell spherical quantum dot
- 2019
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In: Zhongguó wùli xuékan. - : ELSEVIER SCIENCE BV. - 0577-9073. ; 57, s. 189-194
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Journal article (peer-reviewed)abstract
- Using the variational approach within the framework of the effective-mass approximation (EMA), the binding energy of a centred hydrogenic donor impurity in a CdSe/ZnTe core/shell spherical quantum dot (CSSQD) in the presence of an external magnetic field was investigated. In this model, we have taken into account the effect of the radial dependence of the dielectric constant and of the electron effective mass. Our numerical results show a remarkable influence of the nanodot spatial parameters and of the external magnetic field strength on the shallow donor binding energy.
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| 28. |
- Chafai, A., et al.
(author)
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Shallow donor inside core/shell spherical nanodot : Effect of nanostructure size and dielectric environment on energy spectrum
- 2017
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In: Superlattices and Microstructures. - : Elsevier BV. - 0749-6036 .- 1096-3677. ; 111, s. 976-982
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Journal article (peer-reviewed)abstract
- We have reported the impact of the core and shell radii on the energy spectrum of centered shallow donor confined inside CdSe/ZnTe core/shell quantum dot and ZnTe/CdSe inverted core/shell quantum dot. The dielectric discontinuity between the nanosystems and their surrounding medium was considered. In order to examine the behavior of the donor binding energy as a function of the spatial parameters a variational approach within the framework of the effective-mass approximation was deployed. Our model shows that for a fixed shell radius the increase of the core radius value blue-shifts the binding energy of the donor inside inverted core/shell quantum dot only if the value of the core to shell radii ratio is between 0.9 and 1, otherwise it is red-shifted. By contrast, for core/shell quantum dot system the binding energy is red-shifted by increasing the core radius for a fixed nanostructure size and for all values of the core to shell radii ratio. We have also found that the donor binding energy values are more important in a core/shell nanodot than in an inverted core/shell quantum dot.
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| 29. |
- Chafai, A., et al.
(author)
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Tuning the binding energy of on-center donor in CdSe/ZnTe core/shell quantum dot by spatial parameters and magnetic field strength
- 2017
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In: Physica. E, Low-Dimensional systems and nanostructures. - : Elsevier BV. - 1386-9477 .- 1873-1759. ; 94, s. 96-99
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Journal article (peer-reviewed)abstract
- The behavior of the electron ground state and of the ground state binding energy of an on-center donor confined in a CdSe/ZnTe core/shell spherical nanodot was examined theoretically within the framework of the effectivemass approximation and using a variational calculation. The radial dependence of the dielectric constant and of the electron effective mass as well as the effect of the polarization charge were considered. Our results highlight the large impact of the magnetic field strength and the spatial parameters on the energy behavior for both the electron and the donor. Our study points out also the fact that the magnetic confinement may be eclipsed by the spatial confinement in heteronanostructures with small size and expected to be dominant in the opposite case.
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| 30. |
- El Hamri, M., et al.
(author)
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Hysteresis loop behaviors of a decorated double-walled cubic nanotube
- 2017
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In: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 524, s. 137-143
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Journal article (peer-reviewed)abstract
- The effect of surface shell parameters on the hysteresis loop behaviors of a decorated Ising cubic nanotube, consisting of a ferromagnetic spin-12 core which is interacting ferrimagnetically with a ferromagnetic spin-1 surface shell, is investigated, in the present work, within the effective-field theory with correlations based on the probability distribution technique. We have found that these parameters have a strong effect on the shape and the number of hysteresis loops and also on the coercive field and remanent magnetization behaviors. Indeed, triple, quintuple, septuple and nonuple hysteresis loop patterns have also been observed.
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| 31. |
- El Hamri, M., et al.
(author)
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Magnetic behaviors of a transverse spin-1/2 Ising cubic nanowire with core/shell structure
- 2017
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In: Physica. B, Condensed matter. - : Elsevier. - 0921-4526 .- 1873-2135. ; 507, s. 51-60
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Journal article (peer-reviewed)abstract
- The surface shell exchange coupling effect on the magnetic properties (surface shell, core, total longitudinal and total transverse magnetizations, susceptibility, phase diagram and hysteresis loops) of a transverse spin-1/2 Ising cubic nanowire is investigated, in the present work, by employing the effective-field theory based on the probability distribution technique with correlations, for both ferro-and antiferromagnetic cases. We have found that this parameter has a strong effect on the magnetic properties in both cases. In the ferromagnetic case, the total longitudinal magnetization curves display Q-and S-type behaviors and the hysteresis loop has just one loop, whereas in the antiferromagnetic case, the N-type behavior, in which one compensation temperature appears below the critical temperature, exists in the total longitudinal magnetization curve versus reduced temperature, and triple hysteresis loops are found. The effect of applied field is also investigated on the total longitudinal magnetization for the both cases, and we have found that a large applied field value can overcome the antiferromagnetic coupling leading to a ferromagnetic-like behavior.
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| 32. |
- El Hamri, M., et al.
(author)
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Phase diagrams of a transverse cubic nanowire with diluted surface shell
- 2016
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In: Applied Physics A. - : Springer Science and Business Media LLC. - 0947-8396 .- 1432-0630. ; 122:3
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Journal article (peer-reviewed)abstract
- The effective-field theory with correlations based on the probability distribution technique has been used to investigate the phase diagrams (critical and compensation temperatures) of a transverse antiferromagnetic spin-1/2 Ising cubic nanowire with diluted surface shell. It is found that the phase diagrams of the system are strongly affected by the surface shell parameters. Indeed, two compensation points appear for certain values of Hamiltonian parameters, and the range of appearance of these latter points depends strongly on the surface shell transverse field.
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| 33. |
- El Hamri, M., et al.
(author)
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Some characteristic behaviours of a spin-1/2 Ising nanoparticle
- 2016
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In: 3Rd Euro-Mediterranean Conference On Materials And Renewable Energies (Emcmre-3). - : IOP PUBLISHING LTD.
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Conference paper (peer-reviewed)abstract
- By using the effective-field theory with correlations based on the probability distribution technique; the magnetization, susceptibility, internal energy, specific heat and the free energy expressions for a ferromagnetic spin-1/2 Ising nanoparticle have been developed and calculated numerically for different surface shell exchange coupling parameter. A number of interesting phenomena have been observed, depending on the surface shell exchange coupling term.
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| 34. |
- El Hamri, M., et al.
(author)
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Thermodynamic Properties of the Core/Shell Antiferromagnetic Ising Nanocube
- 2015
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In: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 28:10, s. 3127-3133
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Journal article (peer-reviewed)abstract
- Using the effective field theory with correlations, the effects of the exchange interaction on the thermal behaviors of the total magnetization, internal energy, specific heat, entropy, and free energy of a transverse antiferromagnetic Ising nanocube are investigated. The phase diagram is also calculated and discussed in detail.
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| 35. |
- Oubelkacem, A., et al.
(author)
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Effect of Seeding Layers on Hysteresis Loops and Phase Transition of the Ferroelectric Thin Film
- 2015
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In: Ferroelectrics (Print). - : Informa UK Limited. - 0015-0193 .- 1563-5112. ; 478:1, s. 1-10
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Journal article (peer-reviewed)abstract
- The hysteresis loops and the transition properties of a ferroelectric (FE) thin film with seeding layers are studied using the effective field theory with a probability distribution technique that accounts for the self-spin correlation functions. The effect of the interaction parameters for the seeding layer on the hysteresis loops and phase diagram are also examined. We calculated the critical temperature and the polarization of the FE thin film for different seeding layer structures. We find that the seeding layer can greatly increase the Curie temperature and the polarization of the whole FE thin film. The hysteresis loops are obtained for some typical value of the exchange interaction and the transverse field for a film with one or two seeding layers.
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| 36. |
- Oubelkacem, A., et al.
(author)
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The Magnetic Properties of Multi-surface Transverse Ferroelectric Ising Thin Films
- 2015
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In: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 28:3, s. 877-883
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Journal article (peer-reviewed)abstract
- The effective field theory (EFT) based on the transverse Ising model (TIM) is used to study the layer and average polarizations of multi-surface ferroelectric thin film. The effects of the transverse fields and the exchange interactions on the polarization are discussed. It is obvious that the polarizations are affected explicitly by the TIM parameters, and the larger the exchange interactions, the larger the layer and average polarizations. Our theoretical predictions may be a reference for future work in studying the phase transition properties of ferroelectric thin films.
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