Unravelling the linear and biquadratic magnetoelectric coupling in Ba0.95Sn0.05Ti0.95 Ga0.05O3 – CoFe1.8Ga0.2O4 particulate multiferroic composites

Abstract

Since multiferroic composites have substantially stronger magnetoelectric coupling between the order parameters than the single-phase multiferroics, they are more interesting prospects for next-generation multi-state memories and spintronic devices. In light of this, the current work outlines the fabrication of ferroelectric perovskite BaTiO3 and ferrimagnetic spinel CoFe2O4-based particulate multiferroic composites with general formulla (1-x) Ba0.95Sn0.05Ti0.95 Ga0.05O3 – x CoFe1.8Ga0.2O4 (x = 0.04, 0.08 & 0.12). At room temperature, the gallium and tin doping enhanced the dielectric properties of BaTiO3 (ε ´ =9200), and particulate composite (ε ´ =6000) with 12% of CoFe1.8Ga0.2O4 phase. In the same composite, the reduced leakage current density of 3.4 μA/cm2 and improved magnetoelectric properties, with linear and quardatic coupling coefficients of 3.41 mVcm−1Oe−1 and 3.4 × 10−4 mVcm−1Oe−2 were achieved. In composites with a larger magnetic phase, the decrease in cell volume and increased tetragonality produces the compressive strain, that in turn improves the ME coupling. Diffused ferroelectric transitions were ascertained by using the Curie- Weiss Law. Enhanced dielectric properties are linked to decrease in hopping and bond lengths, caused by the incorporation of non-magnetic Ga3+ ions in the CoFe2O4 lattice. A reduction in leakage current density was observed on Sn doping. The calculated square-ness ratios reveal an ordered multi-domain structure. Improved dielectric response along with linear and biquadratic coupling makes these Sn and Ga doped BaTiO3-CoFe2O4 particulate composites as potential candidates for magnetoelectric devices.