scholarly journals Study of the Curie temperature in a transverse Ising film with the next nearest-neighbor interactions

Author(s):  
Z P Li ◽  
Z X Lu
Author(s):  
Lhaj el Hachemi Omari ◽  
Abdelmajid Lekdadri ◽  
Rachid Chami ◽  
El Kibir Hlil

The critical behavior and magnetic properties of Pr0.65Sr0.35MnO3 (symbolized by PSMO) were studied using Monte Carlo simulation (MCS). The thermal bath algorithm and the Ising model in which exchange interactions via the third nearest neighbor were used to calculate the magnetic and magneto-caloric properties. The effects of temperature (T) and external magnetic field (h) on the magnetic behavior of PSMO were examined. The results show that the Curie temperature (TC) is close to the experimental value. The magnetic entropy shows a maximum value around the TC which increases linearly with the increase of the external field. The expected critical behavior of the PSMO nanoparticles was studied through the isothermal magnetization and from the Arrott plots. The obtained values are β = 0.356, γ = 1.121, and δ = 3.95. These values not so far from those reported for the 3D-Ising model. The variation of maximum magnetic entropy (∆S_m^max) and relative cooling power (RCP) around the Curie temperature were calculated; the resulting values of ∆S_m^max and those of RCP range from 3.612 and 92.7 for 1T to 6.191 and 209.9 for 5T, respectively. These results are sufficiently interesting to consider the PSMO compound as a promising candidate for magnetic refrigeration.


2013 ◽  
Vol 23 (3) ◽  
pp. 235
Author(s):  
Pham Huong Thao ◽  
Bach Thanh Cong

The Gaussian spin fluctuation theory is applied to study magnetic properties (Curie temperature, magnetization) of EuO  ultra-thin films within nearest neighbor and next nearest neighbor exchange approximation. The dependence of Curie temperature on the thickness of the free EuO ultrathin film is calculated and compared with the results of the other mean field method- constant coupling approximation. The effect of nearly independence of saturation magnetization on the EuO film’s thickness measured  in [8] can be explained by controlling the next nearest neighbor exchange in presence of substrates.


Author(s):  
J. M. Oblak ◽  
W. H. Rand

The energy of an a/2 <110> shear antiphase. boundary in the Ll2 expected to be at a minimum on {100} cube planes because here strue ture is there is no violation of nearest-neighbor order. The latter however does involve the disruption of second nearest neighbors. It has been suggested that cross slip of paired a/2 <110> dislocations from octahedral onto cube planes is an important dislocation trapping mechanism in Ni3Al; furthermore, slip traces consistent with cube slip are observed above 920°K.Due to the high energy of the {111} antiphase boundary (> 200 mJ/m2), paired a/2 <110> dislocations are tightly constricted on the octahedral plane and cannot be individually resolved.


Author(s):  
S. R. Herd ◽  
P. Chaudhari

Electron diffraction and direct transmission have been used extensively to study the local atomic arrangement in amorphous solids and in particular Ge. Nearest neighbor distances had been calculated from E.D. profiles and the results have been interpreted in terms of the microcrystalline or the random network models. Direct transmission electron microscopy appears the most direct and accurate method to resolve this issue since the spacial resolution of the better instruments are of the order of 3Å. In particular the tilted beam interference method is used regularly to show fringes corresponding to 1.5 to 3Å lattice planes in crystals as resolution tests.


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