II Simposio Internacional de Ciencia de los Materiales

Magnetization reversal, magnetic relaxation and interactions in BaFe12O19

No programado

20m

Centro Demostrativo de Energía Renovables (Quinta de los Molinos)

Poster Síntesis y Caracterización de Materiales Materiales para la conversión y almacenamiento de Energía

Ponente

Jael Cristina Faloh Gandarilla (Facultad de Física, UH)

Descripción

J. Faloh-Gandarilla a, S. Díaz-Castañón b
a Grupo Materiales Ferroicos, Facultad de Física-IMRE, Universidad de La Habana, San Lázaro y L, La Habana C.P. 10400, Cuba, cristina@fisica.uh.cu
b División de Materiales Avanzados, Instituto Potosino de Investigación Científica, San Luis Potosí C.P. 78216, México.

The desirable M hexaferrites’ magnetic properties are in relation to the specific application. Exploring diverse producing methods is justified by the well-known connection existent between the extrinsic magnetic properties of the materials and their microstructural properties. Besides a low cost, high chemical stability and adequate saturation magnetization, M-hexaferrites present as distinctive characteristic a high uniaxial magneto-crystalline anisotropy. These compounds have enormous commercial impact due to magnetic applications that include permanent magnets, ultra high-density memories, and low-loss microwave devices. Lately, magnetoelectric effects have also been encountered in thin films of substituted M-type hexaferrites, adding more interest to this material. Besides these novel properties, in M hexaferrites there are open issues associated to mechanisms of magnetization reversal and magnetic relaxation. In relation to that, coercivity and interactions in BaFe12O19 samples (obtained by two different methods) were studied using remanence curves and magnetic relaxation in addition to microstructural considerations by means of SEM analysis. Following magnetic relaxation formalism, the activation volume was obtained and interactions were evaluated using the δM technique. Even for a coprecipitated sample with a high coercive field (H=5700 Oe), the experimental activation volume indicates a non-coherent mechanism for magnetization reversal and demagnetizing-like interactions were found in this isotropic sample with large aspect ratio particles; also demagnetizing-like interactions were found for a ceramic sample. Finally, the relation between the activation volume and the domain wall thickness is discussed.