**Volume 3, article 1**

**bogoliubov transformation
for
distinguishable particles**

**Volume 3, article 1**

**bogoliubov transformation
for
distinguishable particles**

**M. Holzmann and F. Laloë**

The Bogoliubov transformation is generally derived in the context of identical bosons with the use of "second quantized" a and a

^{†}operators (or, equivalently, in field theory). Here, we show that the transformation, together with its characteristic energy spectrum, can also be derived within the Hilbert space of distinguishable particles, obeying Boltzmann statistics; in this derivation, ordinary dyadic operators play the rote usually played by the a and a^{†}operators; therefore, breaking the symmetry of particles conservation is not necessary.

*Laboratoire de Physique de l'ENS,. LKB and LPS, 24
rue Lhomond, F-75005 Paris, France*

**_________________________**

**Volume 3, article 2**

**High Efficiency CIGSS Thin Film based
Solar Cells and Mini-modules**

** Ahmed Ennaoui**

The highest efficiency for Cu(Ga,In)Se

_{2}(CIGS) thin-film-based solar cells has been achieved with CdS buffer layers prepared by a solution growth method known as the chemical bath deposition (CBD). With the aim of developing Cd-free chalcopyrite-based-thin-film solar cells, we describe the basic concepts involved in the CBD technique. The recipes developed in our laboratory for the heterogeneous deposition for good-quality thin films of ZnO, ZnSe, ZnS are presented. In view of device optimization, the initial formation of chemical-bath-deposited ZnSe thin films on Cu(Ga,In)(S,Se)_{2}(CIGSS) and the subsequent development of the CIGSS/ZnSe heterojunction were investigated by X-ray photoelectron spectroscopy (XPS). The good surface coverage was controlled by measuring changes in the valence-band electronic structure as well as change in the In_{4d}, Zn_{3d}core lines. From these measurements, the growth rate was found to be around 3.6 nm/min. The valence band and the conduction band-offsets E_{V}and E_{C}between the layers were determined to be 0.60 and 1.27 eV, respectively for the CIGSS/ZnSe interface. The energy band diagram is discussed in connection with the band-offsets determined from XPS data. Small and large area CIGSS based solar cells with a CIGSS/Zn(Se,OH)/ZnO structure are produced. A ZnSe thickness below 10 nm has been found to be optimum for achieving a homogeneous and compact buffer layer on CIGSS with an active area efficiency of 15.7%. Using Siemens Solar technology this structure is adapted to fabricate Cd-free CIGSS monolithic mini-modules with efficiencies up to 11.7%.

*University Mohammed V, Physics
Department, Faculty of Sciences, BP 1014 Rabat-Morocco*

**_________________________**

**Volume 3, article 3**

** N. Benayad, L. Khaya and A. Fathi**

The transverse mixed spin Ising system consisting of spin-1/2 and spin-1 with a longitudinal random field is studied within the finite cluster approximation based on single-site cluster theory. The equations are derived using a probability distribution method based on the use of Van der Waerden identities. In the absence of the transverse field, the complete phase diagram in the case of simple cubic lattice is investigated and exhibits interesting behaviours, where the longitudinal field is bimodally and trimodally distributed. The influence of the transverse field on these behaviours are also examined.

*Groupe de Mécanique
Statistique, Laboratoire de Physique Théorique, Faculté des
Sciences Aïn Chock, B.P. 5366 Maarif, Casablanca, Morocco.*

**_________________________**

**Volume 3, article 4**

of a spin-1/2 Ising model in a random

transverse field method

**
L. Bahmad ^{1},
A. Benyoussef^{1},
A. El Kenz^{1},
and H. Ez-Zahraouy^{1,2}**

The effect of a random transverse field (RTF) on the wetting and layering transitions of a spin-1/2 Ising model, in the presence of bulk and surface fields, is studied within an effective field theory by using the differential operator technique. Indeed, the dependencies of the wetting temperature and wetting transverse field on the probability of the presence of a transverse field are established. For specific values of the surface field we show the existence of a critical probability p

_{c}above which wetting and layering transitions disappear.

*1 Laboratoire de Magnétisme et de Physique des Hautes
Energies Université Mohammed V, Faculté des Sciences
Avenue Ibn Batouta, B.P. 1014, Rabat, Morocco.
2 Abdus Salam International Centre For Theoretical
Physics, P.O. Box 586, 34100 Trieste Italy.*

**
_________________________**

**Volume 3, article 5**

high T

**
M. Bouayad ^{1},
M.Laghrissi^{2},
M . Fliyou^{3},
H.Loumrhari^{2}
and M.Chaouch^{4}**

Within the frame work of BCS phonon-mediated pairing with a logarithmic (2D) Van Hove Singularity in the density of states, we study the anisotropy of superconductors gap taking into account the anisotropy of attractive coupling and the coulomb repulsion .The results show that gap is more disperse and can explain some observed experimental data.

PACS numbers :74. 25. J b; 74. 20. Fg. 74. 72. Bk

*1 Faculté Des Sciences et technique
-Fes-Saiss. Route d Immouzar, Fes-Morocco
2 Faculté Des Sciences de Meknes-Morocco
3 Equipe de physique du solide .ENS. BP 5206
Bensouda-Fes-Morocco
4 Faculté Des Sciences Dhar el Mahrez, Fes
Atlas-Morocco*

**_________________________**

**Volume 3, article 6**

on 304 L stainless steel films

**M. Idiri ^{1},
B. Boubeker^{1}**

Internal friction has been measured between 300 and 760K on 304 L stainless steel (SS) using a vibrating reed device. The 0.6 µm thick samples were deposited with ion beam sputtering technique on (100) silicon substrate. It has been shown that the damping level is considerably reduced by annealing between 500 and 760K. The calculated activation energy and the reaction order, using the Johnson-Mehl-Avrami (J-M-H) kinetic enable us to assume that the observed mechanism is closely related to microstructural rearrangements located at grain boundaries.

Key words :304 L Stainless Steel, Ion Beam Sputtering, Internal Friction.

1
UFR : Physique des Milieux Denses et
Matériaux, Faculté des Sciences Ben M’Sik
Casablanca *
Morocco*

2 Laboratoire de Métallurgie Physique,
U.M.R. 6630 C.N.R.S. Université de
Poitiers Bât. S.P.2MI. Bd 3-Téléport 2,

BP 179-86960 Futuroscope cedex - France

3* **
Laboratoire de Mécanique et
Physique des Matériaux,
UMR 6617 C.N.R.S.Ecole
Nationale Supérieure de
Mécanique et d’Aérodynamique,*

BP 109 - 86960 Futuroscope cedex - France.

**_________________________**

**Volume 3, article 7**

Phonons on the Binding Energy

of an impurity in CdSe Quantum Dot

**B.
El Amrani 1 , N. Essbai 2 , M. Fliyou 1 ,
H.Chikhaoui 1 and M. Chaouch 3**

Using a variational approach, the effect of the confined LO-phonon on the binding energy in CdSe Quantum Dot has been calculated. The charge-carrier-phonon coupling is treated within the adiabatic approximation. Our results show that the effect of the confined LO-phonon on the binding energy decreases with the dot size. However the correction of the confined LO-phonon to bound state energy increases with dot size.

PACS number :03

1 Equipe de Physique du Solide E.N.S BP
5206 Bensouda Fès Morocco.

2 Faculté des Sciences & Techniques, Rte
d’Imouzzer , BP 2202 Fès Atlas Morocco.

3 Faculté Des Sciences Dhar el Mahrez ,Fes
Atlas-Morocco

**_________________________**

**Volume 3, article 8**

amorphous Co

**A.
Hassini and A. Bouhdada**

We have studied amorphous Co

_{80-x}Gd_{x}B_{20}alloys prepared by melt spinning technique. The Gd moment at 4.2 K is found to be 7 µ_{B}which agrees with the theoretical value indicating a collinear spin structure. The magnetic compensation at 4.2 K occurs for x close to 10.3. The mean-field theory has been used to explain the temperature dependence of the magnetization. The exchange interactions between Co-Co and Co-Gd atom pairs have also been evaluated.

Laboratoire de Physique des Matériaux et
de Micro-électronique, Université Hassan
II, Faculté des Sciences Ain Chock,

B.P. 5366, Route d’El Jadida, km-8,
Casablanca, Morocco.

**_________________________**

**Volume 3, article 9**

electrical properties of

metal /insulator/semiconductor structures

** Y. Khlifi**^{1,
2}**,
K. Kassmi**^{1}**,
L. Roubi**^{2}**,
R. Maimouni**^{1}

In this paper, we present the results of simulation concerning electrical properties of metal/insulator/semiconductor structures both in the absence and presence of charge in the insulator. After establishing different basic equations in integral forms, we have given these equations analytically by using the Maxwell-Boltzmann approximation. Then, we have analyzed the potentials and electrical fields in the insulator and at the insulator-semiconductor interface in terms of the voltage applied to the structure and the charge density. This has yielded to the analysis of the relative errors made on these electrical parameters as a function of respectively the field in the insulator, the semiconductor doping and the charge density. The obtained results show a validation of the Maxwell-Boltzmann approximation; in particular for the electrical field determination in the structure (error is lower than 1.8%). The errors made by using this approximation are interpreted in term of semiconductor interface degeneracy.

PACS numbers :70., 73.40.Qv

1
Laboratoire d’Electronique Appliquée et
d’Automatique (LEAA), Université Mohamed I^{er},
Faculté des Sciences, Dépt de Physique,
Oujda, Morocco.

2 Laboratoire de Physique du Solide (LPS),
Université Mohamed I er , Faculté des
Sciences, Dépt de Physique, Oujda,
Morocco.

**_________________________**

**Volume 3, article 10**

of metal/ ultra-thin

oxide/ semiconductor structures

**
Y. Khlifi ^{1,
2}, K.
Kassmi^{1},
L. Roubi^{2},
R. Maimouni^{1}**

In this paper we present results of a modeling of the current-voltage characteristics of metal/ultra-thin oxide/semiconductor structures with negatively biased metal gate (V<0), when the oxide thickness varies from 45Å to 80Å. We analyze the theoretical influence of the temperature and Schottky effect on the Fowler-Nordheim (FN) conduction. The results obtained show that these influences depend on the electric field in the oxide and on the potential barrier at the metal/oxide interface. At the ambient temperature, the influence on this potential barrier is lower than 1.5%. However, it can reach 45% on the pre-exponential coefficient of the FN current. It is therefore necessary to consider in the FN classical conduction expression a correction term that takes account the temperature and Schottky effects. These results are validated experimentally by modeling the current-voltage characteristics of the realized structures at high field.

PACS :70., 73.40.Qv

*
1 Laboratoire
d’Electronique Appliquée et d’Automatique
(LEAA), Université Mohamed I ^{er},
Faculté des Sciences, Dépt de Physique,
Oujda, Morocco.
2 Laboratoire de Physique du Solide (LPS),
Université Mohamed I er ,Faculté des
Sciences, Dépt de Physique, Oujda,
Morocco.*

**_________________________**

**
Volume 3, article 11**

of molecules adsorbed on small metallic

spheres : anisotropy and nonlocality effects

**A.
Semlali, B. Labani* and A. Ayadi**

The calculation of Van der Waals induced polarization of molecules interacting with small metallic spheres is based on the spherical-tensor theory by using the response field susceptibility of the sphere. The first Euler angle appearing in the expression giving this polarization exhibits the anisotropy of the molecule. In order to illustrate the non locality and anisotropy effects as well as the importance of the metallic sphere curvature on the induced polarization magnitudes, we present numerical results for typical systems (HF, HCl) on (Ag, Al and Cu).

L.P.M.C , Département de Physique, Faculté
des Sciences, B.P 20, El jadida, Morocco.

* Département de Physique, Faculté des
Sciences Semlalia, B.P S15, Marrakech,
Morocco.

**_________________________**

**Volume 3, article 12**

CdTe/CdS heterojunction

**M.
Rami, E. Benamar, M. Fahoume, F. Chraibi,
and A. Ennaoui**

CdS/CdTe heterojunction was subjected to chemical treatment commonly used in photovoltaic device fabrication to determine the resulting microscopic effect on the morphology and structure. CdS and CdTe thin films were electrodeposited successively onto indium tin oxide (ITO) from aqueous solution. Containing CdCl

_{2}and Na_{2}S_{2}O_{3}for the deposition of thin film windows, the ITO/CdS resulting substrates was then used for the deposition of CdTe thin film absorber using aqueous solution of CdSO_{4}and TeO_{2}. Next CdCl_{2}dip followed by 400°C heat treatment was used to modify the CdTe/CdS surface and interface. Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) were used to evaluate the resulting surface morphology. X-ray diffraction analysis reveals that the heat treatment enhances the recrystallisation and shifts the CdTe peaks towards a smaller lattice parameter.

Laboratoire de physique des matériaux,
Département de Physique, Faculté des
Sciences de Rabat,

B. P. 1014 Rabat-Morocco.

**_________________________**

**Volume 3, article 13**

thin films prepared by electrodeposition

**E.
Benamar, M. Rami, M. Fahoume, F. Chraibi
and A. Ennaoui**

The cadmium chalcogenides CdSe

_{x}Te_{1-x }(0≤x ≤1 ) thin films have been electrodeposited onto ITO coated glass substrates from an acid sulphate solution at 90 °C. The structure, the composition and the morphology have been studied as a function of the x coefficient by XRD, EDAX, optical absorbance and AFM techniques. All deposits have a cubic structure with a preferred orientation along the (111) direction. The composition in the films is found to vary linearly with the composition in the solution. The increase of the amount of tellurium in the CdSe_{x}Te_{1-x}films decreases the band gap down to 1.35 eV and increases the lattice constant. The photoelectrochemical studies in a polysulfide electrolyte show that CdSe_{x}Te_{1-x}thin films behave as n-type semiconductors.

*Université M ed V Agdal, Faculté des
Sciences, Département de Physique,
Laboratoire de Physique des matériaux.
B.P. 1014 Rabat -Morocco.*

**_________________________**

**Volume 3, article 14**

Effect of growth parameters on the electrical

and thermoelectrical properties

**B.
Aboulfarah**^{1}**,
D. Sayah**^{1}**,
A. Mzerd**^{1}**,
A. Giani**^{2}**,
A. Boyer**^{2}

The growth of (Bi

_{1-x}Sb_{x})_{2}Te_{3}thin films by metal-organic chemical vapour deposition (MOCVD) using trimethylbismuth, triethylantimony and diethyltellurium as bismuth, antimony and tellurium sources respectively is investigated on pyrex substrates. The electrical and thermoelectrical properties of this material are also measured over the growth temperature range 360-470°C. The studies are also made on the effect of VI/V ratio on these properties in the variation range 2-9. Polycrystalline structure is confirmed by X-ray diffraction, and it is observed that the intensity of the preferred orientation is higher at 450°C. The measurement of Seebeck coefficient shows that all samples have p-type conduction. The best value of this parameter is obtained for high growth temperature (240µV/K). The good result obtained for (Bi_{1-x}Sb_{x})_{2}Te_{3}thin films revealed the great potential of MOCVD method which is an industrial technique to produce good materials for device applications (sensors and thermopiles).

1
Université M ed V Agdal, Faculté des
Sciences, Département de Physique,
Laboratoire de Physique des Matériaux,
Rabat, Morocco.

2 Centre d'Electronique et de
Micro-Optoélectronique de Montpellier
(CEM2), UM II, UMR 5507 CNRS, Place E.
Bataillon,

34095 Montpellier cédex 05, France.

**_________________________**

**Volume 3, article 15**

**A
. Riahi , K . Laghdas, S . Rachafi**

Total and single differential cross sections have been calculated for electron impact ionization of Ar

^{10+}(1s^{22}s^{22}p^{4})^{3}P^{e}using a method that combines the distorted-wave Born approximation and R-matrix theory. In this method, the incident/scattered electron is described by the distorted-wave Born approximation, while both the initial bound state and the final continuum states are expanded in terms of an R-matrix basis. Eight states of the final Ar^{11+}ion are considered, namely 1s^{2}2s^{2}2p^{3}^{4}S^{o}^{2}D^{o}^{2}P^{o}and 1s^{2}2s2p^{4}^{4}P^{e}^{2}D^{e}^{2}S^{e}^{2}P^{e}^{2}P^{o}.Up to the 2

^{4}- pole components of the interaction with ionizing electron were included, giving ten distinct Ar^{10+}continuum symmetries. We calculated single differential cross sections summed over final ionic states, as a function of the energy loss. These cross sections exhibit considerable structure due to autoionizing resonances. Total cross sections for production of Ar^{11+}in each of the eight states are presented for impact energies from threshold energy at 19.8 au to 200 au. Our theoretical values for the total cross section are in good agreement with recent experimental results.

Département de Physique, Faculté des Sciences, Université Chouaib Doukkali, B.P. 20, 2400 ElJadida, Morocco

**_________________________**

**Volume 3, article 16**

[Co

sandwiches on the Cu deposition pressure:

Correlation of the “CoZrCu” disordered

phase concentration and the interfacial

mixed zone thickness with the Cu pressure

**M.
Faris ^{1,*}, M. EL Harfaoui^{1},
A. Qachaou^{1}, J. Ben Youssef^{2},**

H. Le Gall^{2}, and D. Meziane. Mtalsi^{1}

The magnetoresistance (MR) and the saturation resistivity (ρ

_{s}) are studied versus the Cu deposition pressure (P_{Cu}) at room temperature, in [Co98Zr2 (25Å)/Cu (t_{Cu}) /Co (25Å)] magnetic sandwiches prepared by RF diode sputtering. Results of low angle X-Ray Diffraction patterns have been proved the importante interfacial degradation observed in (CoZr/Cu) multilayers, compared to the usual (Co/Cu) structures. The highest value of transverse MR is obtained along the easy axis, and the MR curve saturates in a small magnetic field of 100 Oe at room temperature. Which leads to an interesting increase in MR sensitivity about 2%/Oe. The main features of the magnetoresistive properties evolution with Cu deposition pressure are: The maximum of MR increases and moves towards larger Cu thicknesses (t_{Cu}) for increasing P_{Cu}. The saturation resistivity ρs decreases with increasing t_{Cu}while it increases versus P_{Cu}. The satisfactory agreement between our experimental results and calculated ones in the framework of the Johnson-Camley semi-classical model, allows us to interpret the MR and ρ_{s }behavior as a result of a reinforcement of the disordered phase ″CoZrCu″ inside the mixed zone whose thickness t_{mx}increases with P_{Cu}.

1
Laboratoire de Physique de la Matière
Condensée (LPMC) B.P:133-14000
Kénitra-Morocco

2 CNRS, LPS, Groupe de Magnétisme, 92 195
Meudon, France

**_________________________**

**Volume 3, article 17**

in (Ni 80 Fe 20 /Cu) multilayers

**D. Meziane
Mtalsi**^{1}**,
M. EL Harfaoui**^{1}**,
A. Qachaou**^{1}**,
M. Faris**^{1}

**J.
Ben Youssef**^{2}**
and H. Le Gall**^{2}

The dependence of the magnetoresistance (MR) ratio on the thicknesses of the magnetic (m) and non magnetic (nm) layers is studied for Ni

_{80}Fe_{20}/Cu soft magnetic multilayers with a fixed number of bilayers (12). The highest value of the MR is 17,3% at Cu layer thickness of 7 Å. Very high sensitivity, around 132%/kOe has been observed. We present a discussion of the MR results using the Johnson-Camley semiclassical model based on the Boltzmann transport equation.

1
Laboratoire de Physique de la Matière
Condensée(LPMC) B.P:133-1400
Kénitra-Morocco

2 CNRS, LPS, Groupe de Magnétisme, 92 195
Meudon, France

**_________________________**

**Volume 3, article 18**

Fe

**E. Loudghiri**^{1}**
, A. Belayachi**^{1,*}**
, M. Nogues**^{2}**
, M. Taibi**^{3}**
,
A. Dahmani**

Mixed oxides with formula LaFe

_{1-x}Cr_{x}Oand Fe_{3}_{2-2x}Cr_{2x}O, where 0≤x≤1, are studied. The samples have been prepared using solid state reaction technique in air. The X-ray diffraction spectra indicated that the samples crystallize in a corundum phase with space group ( R3c ) for Fe_{3}_{2-2x}Cr_{2x}Oand in the perovskite structure for_{3}

LaFe_{1-x}Cr_{x}O. Many techniques have been used to explore the magnetic properties of the systems. High field, ZFC and FC magnetization vs. temperature, d.c. susceptibility and Mössbauer spectroscopy were carried out. High temperature magnetic susceptibility measurements and high field magnetic magnetization (H ≤ 20 T) show that the behavior of the susceptibility and the magnetization are complex. Mössbauer spectra of the solid solutions have been measured at 4.2 K and in the temperature range 77 K to 300 K. The shapes of spectra are unusual, showing strong relaxation phenomena in a wide temperature range as recently observed for many frustrated systems. The results are discussed by establishing the existence of various magnetic structures, inducing intermediate magnetic phases between the antiferromagnetic and the paramagnetic states. Preliminary magnetic phase diagrams of the systems have been established._{3}

1
Laboratoire de Physique des Matériaux,
Faculté des Sciences Université Mohammed
V,

B.P. 1014 Rabat, Morocco.

2 Laboratoire de Magnétisme et d’Optique
de l’Université de Versailles (URA 1531),
Batiment Fermat, 45 Avenue des Etats Unis,
78035 Versailles Cedex, France.

3 Laboratoire de Physico-Chimie des
Matériaux associé à l’AUF (LAF 502), Ecole
Normale Supérieure Takadoum

B.P. 5118 Rabat Morocco.

**_________________________**

**Volume 3, article 19**

**H. Hamouda**^{a}**
, M. Abid**^{b}**
and D. Saifaoui**^{a}**
and R.Krishnan**^{c}

We have studied the magnetization in Co

_{86}Tb_{14}/Pt multilayers under fields up to 1.8 T and as at room temperature. As the do-Tb layer thickness (t_{CoTb}) decreases below 200 Å the saturation magnetization magnetization (M) increases, the rectangularity of the M-H loops and the coercivity (H_{c}) decrease. The effective anisotropy K_{eff}of the multilayers was determined by a torque magnetometer. The product K_{eff}×t_{CoTb}shows a linear dependence with t_{CoTb}as normally found for the superlatices yielding the bulk and surface anisotropies of 10^{6}erg/cm^{3}and –0.2 erg/cm^{2}, respectively. These results are explained in terms of an interfacial Co-Pt layer. K_{eff}and H_{c}are related by the equation H_{c}= α K_{eff}^{n}/M with the fitting parameters α and n.

a
Laboratoire de Physique Théorique,
Université Hassan II, Faculté des
Sciences, B.P. 5366 Maârif, Ain Chock,

Route d’El Jadida km-8, Casablanca, Morocco.

b Laboratoire de Physique des Matériaux et
de Microélectronique, Université Hassan
II, Faculté des Sciences,

B.P. 5366 Maârif, Ain Chock, Route d’El Jadida km-8,
Casablanca, Morocco.

c Laboratoire de Magnétisme et d’Optique
de l’Université de Versailles, CNRS, URA
1531, 45, Avenue des Etats-Unis,

78035 Versailles cedex, France.

**_________________________**

**Volume 3, article 20**

the extended irreversible

thermodynamics theory

**A.Bourhaleb**^{1,2}**
, A.Salhoumi**^{1}**
, Y.Boughaleb**^{1,*}**
and M.Fliyou**^{2}

The transport in miniaturised electronic devices requires to go beyond simple hydrodynamic descriptions. So, carrier transports in nano-length devices is no longer dominated by collisions among the particles but the ballistic transport governs at this level. This type of transport occurs when the perturbation characteristic time is of the order of the relaxation time and the mean free path is of the order of the device's dimension. The aim of the present work is to calculate the ballistic velocity of heat transport by using a continued-fraction technique in the framework of extended irreversible thermodynamics. This ballistic speed must be less or equal to the maximum value

c_{0}corresponding to phonon speed. Note that the classical Fourier equation is only able to describe the diffusion regime and the Maxwell-Cattaneo equation predicts a second sound propagation at speedc/Ö3 but it is silent about the ballistic behaviour ._{0}

1
Laboratoire de Physique de la Matière
Condensée, Faculté des sciences Ben M'Sik,
BP 7955 Ben M'Sik Casablanca, Morocco.

2 Equipe de l’énergie solaire E.N.S
Marrakech, Morocco.

**_________________________**

**Volume 3, article 21**

**H. Hamouda**^{1}**
, D. Saifaoui**^{1}**
and H. Lassri**^{2}

We report here our magnetic study on amorphous Gd

_{0.7}Zr_{0.3}alloy. The magnetic saturation is difficult to obtain even for fields up to 50 kOe. This led us to the conclusion that ferromagnetic and antiferromagnetic clusters are present in this alloy. However, the presence of a well defined T_{c}indicate that the ferromagnetic clusters are dominant and he presence of the coherent anisotropy field can transform this type of magnetic ordering into a ferromagnetic domain structure. The thermomagnetization curve is found to obey the Bloch law, spin wave stiffness constant and the distance between nearest magnetic atoms were calculated from the experimental results.

1
Laboratoire de Physique Théorique.
Université Hassan II, Faculté des Sciences
Ain Chock, B.P. 5366, Route d’El Jadida,
km-8, Casablanca, Morocco.

2 Laboratoire de Physique des Matériaux et
de Micro-électronique. Université Hassan
II, Faculté des Sciences Ain Chock,

B.P. 5366, Route d’El Jadida, km-8, Casablanca, Morocco.

Copyright © The Moroccan Statistical Physical Society. [mjcm@fsr.ac.ma]. Last modification : July 2010.

**ISSN : 1114-2073**