Magnetization reversal and interactions in SrFe₁₂O₁₉

Abstract

Coercivity and interactions in coprecipitated and ceramic SrFe12O19 (Sr‐M) hexaferrite samples were studied using remanence curves and magnetic viscosity in addition to microstructural considerations by means of SEM analysis. Following a magnetic viscosity formalism, the activation volume was obtained and interactions were evaluated using the ΔM technique. Even for a coprecipitated sample with a high coercive field (Hc = 6100 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 thermally treated coprecipitated sample and a ceramic sample.

Coercivity global model and magnetization reversal in fine hexaferrites

“…It can be noted that the room temperature coercive field, H c = 6100 Oe for SrFe 12 O 19 and H c = 5700 Oe for BaFe 12 O 19 , are below the value predicted by the Stoner–Wohlfarth model , but represent approximately the 80% of that theoretical estimation. Demagnetizing‐type interactions, which are not considered in SW model, have been encountered in this SrFe 12 O 19 sample earlier . It was observed that the effect of the interaction on the magnetization reversal is the strongest near the switching field, presumably lowering the experimental coercive field.…”

Coercivity and Interactions in Sr–M Thin Films with Nonperpendicular Orientation

“…Figure shows the activation volume dependence on applied field. These activation volume values, V a ≈ 8 × 10 −18 cm 3 , are lower than those obtained for the bulk samples (ceramic and coprecipitated samples) . However, the activation volume is two orders of magnitude lower than the average physical particle volume.…”

“…These activation volume values, V a % 8 Â 10 À18 cm 3 , are lower than those obtained for the bulk samples (ceramic and coprecipitated samples). [17,33] However, the activation volume is two orders of magnitude lower than the average physical particle volume. It points to a reversal mechanism different from coherent rotation, as was also reported in the study by Faloh-Gandarilla et al [17] for the bulks samples, and in agreement with the absolute value of coercivity encountered which is a fraction of the anisotropy field.…”

“…This sample constituted interesting systems for the study of particle interactions because they are formed mainly by hexagonal platelets with their easy axis of magnetization perpendicular to the hexagonal plane. A preview report on these topics has already been published but in bulk samples obtained by the ceramic and chemical coprecipitation methods …”

“…A preview report on these topics has already been published but in bulk samples obtained by the ceramic and chemical coprecipitation methods. [17] In this work, Sr-M (SrFe 12 O 19 ) polycrystalline thin films were deposited on Si single-crystal substrates using the pulsed laser ablation deposition (PLAD) technique. PLAD is a useful deposition technique for growing complex and multicomponent materials; several types of materials have been successfully deposited using PLAD.…”