A critical evaluation of the 0–3 approach for magnetoelectric nanocomposites with metallic nanoparticles

Abstract

Granular nanocomposite films with embedded metallic particles have been suggested as a promising material class for magnetoelectric (ME) applications. We present a thorough case study of nanogranular aluminum nitride (AlN)/cobalt (Co) composites accompanied by finite element simulations. The present study shows that the use of metallic nanoparticles in 0–3 nanocomposites has fundamental limitations for the development of ME materials. AlN/Co films are deposited by magnetron co-sputtering with a gas aggregation cluster source, allowing the direct investigation of the cluster influence on the structural properties of the matrix under otherwise identical deposition conditions. While commonly leakage currents are perceived as the major challenge of the granular approach, our findings indicate further inherent hindrances. Apart from an increase of dielectric losses tanδ with increasing cobalt content, we find a drastic degradation of matrix crystallinity already at very low filling factors and a pronounced increase in dielectric permittivity εr. In addition, finite element simulations indicate a local short circuiting of the matrix, reducing the electric polarization. In the face of our results, existing literature on ME 0–3 nanocomposites with metallic particles is critically discussed.