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Magnetic Properties of Antiferromagnetic Thin Films with spin S
R. Masrour,M. Hamedoun,E. K. Hlil,A. Benyoussef 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.7
The mean field theory (MFT) and high temperature series expansions (HTSEs) of the magneticsusceptibility are used to investigate the magnetic properties in simple cubic (sc) antiferromagneticwith spins S = 1 and S = 3/2 films by using both the Ising and the XY models. The films consistingof l = 2, 3, 4, 5, 6 and infinite (1) interacting layers are studied up to sixth order series in x = Jwhere = 1kBT , for free-surface boundary conditions. The effects of finite size on the critical-pointbehavior are studied by extrapolation of the high-temperature series. The N´eel temperature TN(l)as a function of the spin layers numbers l is obtained by using HTSEs of the magnetic susceptibilityseries, the Pad´e approximant method and the MFT theory. The critical exponentassociatedwith the magnetic susceptibility is deduced. The N´eel temperatures TN(l) for the l-layers films areestimated from the divergence of the staggered susceptibility with exponents(1) and(2) for theIsing and the XY models, respectively. This is consistent with the basic assumptions of scalinglaws. The shift exponents of the N´eel temperature for the Ising and the XY models, respectively,are estimated.
O. Hassayoun,M.R. Laouyenne,M. Baazaoui,E.K. Hlil,M. Oumezzine,Kh. Farah 한국물리학회 2019 Current Applied Physics Vol.19 No.12
The research results of magnetocaloric effect and critical properties of La0.8Na0.2Mn1-xNixO3 (0≤x≤0.06) manganite are reported. Using the Banerjee's criteria, Franco method and Landau theory, we proved the second order ferromagnetic-paramagnetic phase transition for all samples. The critical exponents values β, γ and δ are determined using modified Arrott plot (MAP), Kouvel Fisher technique and the critical isotherm. Indeed, comparing our determined exponent values with those of standards model, there is a shifting tendency from the mean field model for the compositions La0.8Na0.2MnO3 and La0.8Na0.2Mn0.97Ni0.03O3 to those of the 3D-Ising model for La0.8Na0.2Mn0.94Ni0.06O3 sample. Thus, reflect that the magnetic coupling tends to change from the long-range to the short-range interaction as increasing Ni content. Particularly, by performing the Landau theory we suggest that the magnetoelastic contribution and the electron interaction should be associated with the Jahn Teller interaction in the determination of ΔSM magnetic entropy change effect in our compounds.
D. Turki,Zafar Khan Ghouri,Saeed Al-Meer,Khaled Elsaid,M. I. Ahmad,Ahmed Easa,M. Ellouze,E. K. Hlil 한국자기학회 2017 Journal of Magnetics Vol.22 No.3
The physicochemical properties of La0.8Ca0.2Mn1−xCoxO₃ nanopowders as a function of Co content (x) have been investigated. La0.8Ca0.2Mn1−xCoxO₃ nanopowders were synthesized by sol-gel method and morphologically and structurally well characterized by Scanning electron microscopic (SEM), Infrared spectroscopic (IR) and Raman spectroscopic techniques. IR spectra shows peak at around 600 cm<SUP>−1</SUP> attributed to the stretching mode of MnO6 octahedral and peak at 700 cm<SUP>−1</SUP> assigned to La-Ca-O-Mn bending vibrations. Raman spectra indicate peaks at around 512 and 652 cm<SUP>−1</SUP> related to the Jahn-Teller octahedral distortions. The intensity of these peaks increases with increasing Co doping. The UV-visible spectra were measured in the frequency range of 200-800 nm and two energy gaps were found at 1.63 eV and 3.294 eV for x = 0, 0.1 and 0.3.