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(18) Production(s) de CHARAR S.
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Crystal-field investigations and magnetic properties of Nd3+-doped Bi4Si3O12 
Auteur(s): Isber S., Tabbal M., Christidis T., Charar S., Terki F., Ishii M.
(Article) Publié:
Physical Review B, vol. 71 p.014405 (2005)
Ref HAL: hal-00549878_v1
DOI: 10.1103/PhysRevB.71.014405
WoS: 000226735100085
Exporter : BibTex | endNote
6 Citations
Résumé: The magnetic properties of bismuth silicate (BSO) doped with Nd3+, Bi4(1-x)Nd4xSi3O12 (x=0.5%, 1.5%, 2.5%, 3.5%, and 5%) were investigated. X-band electron paramagnetic resonance measurements show that the site symmetry of Nd3+ at 4.2 K is trigonal and the Lande factors were determined to be g(parallel to)=1.15+/-0.01 and g(perpendicular to)=2.47+/-0.02. The exchange coupling between nearest-neighbor (NN) Nd3+ ions was estimated from magnetization measurements, using a model that takes into account the magnetic contributions of single ions and pairs. The exchange interaction between Nd3+ nearest neighbors is antiferromagnetic with an estimated value of J(p)/k(B)=-5.2+/-0.4 K. The energy levels splitting of Nd3+ were obtained from optical absorption spectra measurements at 300, 77, and 5 K.
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Postgrowth annealing of (Ga,Mn) As under As capping: An alternative way to increase T-C
Auteur(s): Adell M., Ilver L., Kanski J., Stanciu V., Svedlindh P., Sadowski J., Domagala Jz, Terki F., Hernandez C., Charar S.
(Article) Publié:
Applied Physics Letters, vol. 86 p.112501 (2005)
Texte intégral en Openaccess : 
Ref HAL: hal-00549879_v1
DOI: 10.1063/1.1875746
WoS: 000228050700056
Exporter : BibTex | endNote
51 Citations
Résumé: In situ postgrowth annealing of (Ga,Mn)As layers under As capping is adequate for achieving high Curie temperatures (T-C) in a similar way as ex situ annealing in air or in N-2 atmosphere practiced earlier. Thus, the first efforts give an increase of T-C from 68 to 145 K after 2 h annealing at 180 degrees C. These data, in combination with lattice parameter determinations and photoemission results, show that the As capping acts as an efficient sink for diffusing Mn interstitials. (C) 2005 American Institute of Physics.
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Exchange coupling in spins quartet of dimeric polyoxoanions [M-4(H2O)(2)(GeW9O34)(2)](12-) (M = Mn2+, Cu2+)
Auteur(s): Isber S., Tabbal M., Christidis T., Terki F., Charar S.
Conference: Joint European Magnetic Symposia (JEMS 04) (Dresden (GERMANY), FR, 2004-09-05)
Actes de conférence: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, vol. 290 p.985-988 (2005)
Ref HAL: hal-00539824_v1
Exporter : BibTex | endNote
Résumé: Magnetization and magnetic susceptibility of dimeric polyoxoanions [M-4(H2O)(2)(GeW9O34)(2)](12-) (M = Mn2+, Cu2+) were investigated using an isotropic exchange coupling model with two coupling constant (J and Y) within the spin quartet formed by M4O16 (M = Mn2+, Cu2+). The exchange couplings were found to be antiferromagnetic for both samples with the values (J/k(B) = -0.91 ± 0.04 K and J'k(B) = - 1.18 ± 0.02 K) and (J/k(B) = - 13.5 ± 0.5 K and J'/ k(B) = -66 ± 4 K) for the samples containing Mn2+ and Cu2+, respectively. Furthermore, X- and Q-Band powder electron paramagnetic resonance (EPR) measurements on the sample containing Cu2+ were investigated and the experimental spectra were simulated using a triplet spin state S = 1 and I = 3, and including a small axial distortion D term. This leads to spin-Hamiltonian parameters of: | D| = 0.44 ± 0.01 GHz, g|| 2.415 ± 0.005, g⊥ = 2.070 ± 0.005, A(ii) = (40 ± 1) G. © 2004 Elsevier B.V. All rights reserved.
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Experimental determination of the phonon density of states in filled skutterudites: evidence for a localized mode of the filling atom
Auteur(s): Viennois Romain, Girard L., Koza M.M., Mutka Hannu, Ravot Didier, Terki F., Charar S., Tedenac J.C.
(Article) Publié:
Physical Chemistry Chemical Physics, vol. 7 p.1617 (2005)
Texte intégral en Openaccess : 
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