Improved magnetodielectric coefficient on polymer based composites through enhanced indirect magnetoelectric coupling

Particulate composites of ferrite and ferroelectric polymer phases with general formula [xCoFe2O4]/[(1-x) PVDF] were prepared for x = 0, 3, 11 and 20 wt.% by solution casting. The dielectric constant, dielectric loss and saturation magnetization of the polymer composite films increase with increasing CoFe2O4 (CFO) content, being 13, 0.13 and 13 emu.g-1 respectively, for x=20. The magnetodielectric (MD) coupling also depend on the CFO content, the change in the dielectric response (MDE(%)) being the highest for the x=20 sample (4.2%). On the other hand, the highest value of the MD coefficient (γ) is higher on the x=3 sample (0.015 emu-2g2). Those values are favourably compared with the ones found in the ceramic-based MD materials, being the highest reported for polymer composites. These facts, together with the flexibility and scalable production of the composites, leads to their large application potential in areas such as filters, magnetic field sensors and actuators, among others.The authors thank the Portuguese Fundação para a Ciência e Tecnologia (FCT) for financial support under projects PTDC/EEI-SII/5582/2014 and PTDC/CTM-ENE/5387/2014.P. M. and M. Silva acknowledges also support from FCT (SFRH/BPD/96227/2013 and SFRH/BD/70303/2010 grants respectively). Financial support from the Basque Government Industry Department under the ELKARTEK Program is also acknowledged. SLM thanks the Diputación Foral de Bizkaia for financial support under the Bizkaia Talent program; European Union’s Seventh Framework Programme; Marie Curie Actions – People; Grant agreement nº 267230