Magnetic properties of Fe1/CrN nanoinclusions in Fe
P.G. Alvarado-Leyva1, J.M. Montejano-Carrizales2, J.L. Morán-López3
1 Departamento de Física, Facultad de Ciencias, Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, S.L.P., México.
2 Instituto de Física, "Manuel Sandoval Vallarta", Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, S.L.P., México.
3 Instituto Potosino de Investigación Científica y Tecnológica, Apartado Postal 3-74 Tangamanga, 78231 San Luis Potosí, S.L.P., México.
]]>Recibido el 11 de marzo de 2002.
Aceptado el 21 de agosto de 2002.
Abstract
The magnetic properties of Fe1 /CrN inclusions in a Fe matrix are calculated as a function of the Cr number of atoms N at zero temperature, and for N ≤ 168. The electronic structure is determined by using a realistic spd-band Hamiltonian. The local magnetic moments μ(i) at the various cluster sites i are calculated selfconsistently in the unrestricted Hartree-Fock approximation. The results show clearly the importance of the local geometry and the magnetic interactions between neighbors. The matrix Fe atoms couple always antiferromagnetically to the Cr atoms, imposing for small N spin arrangements that overcome the antiferromagnetic interactions of the Cr cluster. The antiferromagnetic arrangement becomes possible in the interior of the cluster as the number of Cr atoms becomes larger than 88.
Keywords: Nanoinclusions; magnetic properties; magnetic local moments.
Resumen
Se calculan las propiedades magnéticas de inclusiones de Fe1 /CrN en una matriz de Fe, como una función del número N de átomos de Cr, a temperatura cero y valores de N ≤ 168. La estructura electrónica se determina usando un hamiltoniano que toma en cuenta electrones de los tipos s, p y d. Usando la aproximación irrestricta de Hartree-Fock se calcula autoconsistentemente el momento magnético local μ(i) en los diferentes sitios i del cúmulo. Los resultados muestran claramente la importancia de la geometría local y las interacciones magnéticas entre vecinos. Los átomos de Fe de la matriz se acoplan siempre antiferromagnéticamente a los átomos de Cr, imponiendo arreglos de espín que sobrepasan el antiferromagnetismo entre iones del cúmulo de Cr para valores pequeños de N. Los arreglos anti ferromagnéticos se presentan dentro del cúmulo de Cr cuando el numero de átomos de Cr es más grande que 88.
]]> Descriptores: Inclusiones nanométricas; propiedades magnéticas; momentos locales magnéticos.
PACS: 75.50.Rb
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Acknowledgements
This work was done under the auspices of CONACyT (México) through grants G-25851-E and W-8001 (Millennium Initiative). One of the authors (P.G.A.L.) acknowledges to FAI-UASLP (México) under contract C00-FAI-11-13.76.
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