Magnetic properties of SrFe12O19 covered with copper by electrodeposition and sputtering

• Published in: Ceramics international Vol. 45; no. 17; pp. 22675 - 22681
• Main Authors: García‐Gallegos, J.H., Mirabal-García, M., Aranda-Espinoza, S., Cabal-Velarde, J.G., Ramírez, J.M. Olivares, Lobo-Guerrero, A.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2019
• Subjects: Chemical electrodeposition; Copper deposition; Differential susceptibility curve; Hexaferrite magnet; Sputtering; Copper deposition; Differential susceptibility curve; Chemical electrodeposition; Sputtering; Hexaferrite magnet
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2019.07.302

This work reports the micromagnetic properties of the strontium hexaferrite (SrM) when its surface is covered with a copper layer. The copper was deposited on the hexaferrite using two different methods, one based on the electrochemical deposition and the other one, using the magnetron sputtering technique. For each fabrication method, two different deposition times were selected to vary the copper quantity over the hexaferrite surface. The structural and morphological properties were analyzed from the X-ray diffraction patterns and scanning electron micrographs, while the magnetic behavior was investigated using alternating gradient magnetometry measurements. The samples obtained from chemical electrodeposition exhibited inhomogeneous copper deposits, while the ones obtained from sputtering presented homogeneous and well-distributed copper deposits. The results showed marked differences in the magnetic properties of the hexaferrite with deposited copper regarding the SrM without copper. Also, an improvement in the magnetic properties was observed when a homogeneous copper layer was deposited using sputtering than when electrodeposition was used. When copper was homogeneously deposited, the coercivity (Hc) exhibited an improvement from 2.5 kOe to 3.56 kOe, whereas the remanence squareness (Mr/Ms) increased from 0.5 to 0.7, which is equivalent to 40% increment as a consequence of the copper presence. The changes observed in the hysteresis loops and the dM/dH, H curves indicate that copper exerts a strong interaction on the magnetic moments of hexaferrite. This interaction couples the copper atoms with the interstitial cations of the hexaferrite structure. This copper-iron interaction would occur through a Cu–O–Fe superexchange mechanism, varying the intrinsic properties of the hexaferrite and modifying its micromagnetic behavior.