Electrodeposition of Hybrid Magnetostrictive/Magnetoelectric Layered Systems.

The potential use of electrodeposition to synthesize a hybrid magnetostrictive/magnetoelectric layered system is shown in this paper. By appropriately adjusting pH, growth potential, and electrolyte composition, it is possible to achieve thin films in which magnetoelectric oxide GaFeO3 (GFO) is formed in close contact with magnetostrictive metallic FeGa alloy. X-ray diffractometry shows the formation of FeGa as well as GFO and Fe oxides. Electron microscopy observations reveal that GFO mainly segregates in grain boundaries. Samples are ferromagnetic with an isotropic magnetic behavior in the sample plane. Magnetic stripes are observed by magnetic force microscopy and are correlated to Fe3O4. When its segregation is minimal, the absence of stripes can be used to monitor Fe oxide segregation.

Synthetic domain walls in [TbFeGa/TbFe]2 multilayers.

Here we report the possibility of creating synthetic domain walls in nominal [Fe72Ga28/Tb33Fe67]2 multilayers. The magnetization as a function of the temperature reveals the absence of Compensation temperature in the samples which can be understood considering an interdiffusion process that results in the formation of TbFeGa alloys at the nominal FeGa layers. Therefore, samples actually comprise TbFeGa and TbFe layers. The hysteresis loops exhibit magnetization steps related to the nucleation of domain walls formed because of the competition between different interactions: (i) the antiferromagnetic exchange coupling between the heavy rare earth (Tb) and the transition magnetic metal (Fe) inside each layer, (ii) the antiferromagnetic coupling between Tb and Fe at the interfaces, and (iii) the Zeeman energy. In good agreement with the experimental values, the nucleation field of the domain walls has been theoretically calculated taking into account the tilt of the magnetization with respect to the sample plane. Our experimental results indicate that by a proper thickness adjustment, it can be tuned, both the value of the nucleation field and the layer in which this firstly occurs. Experimental values for the exchange bias field have also been calculated.

Antiferromagnetic FeMn alloys electrodeposited from chloride-based electrolytes.

The capability of synthesizing Fe-based antiferromagnetic metal alloys would fuel the use of electrodeposition in the design of new magnetic devices such as high-aspect-ratio spin valves or new nanostructured hard magnetic composites. Here we report the synthesis of high quality antiferromagnetic FeMn alloys electrodeposited from chloride-based electrolytes. We have found that in order to grow homogeneous FeMn films it is necessary to incorporate a large concentration of NH4Cl as an additive in the electrolyte. The study of the structure and magnetic properties shows that films with composition close to Fe50Mn50 are homogeneous antiferromagnetic alloys. We have established a parameter window for the synthesis of FeMn alloys that show antiferromagnetism at room temperature.