Enhanced magnetic and magnetodielectric behavior in morphologically distinct BTFO and LSMO composites

Abstract

In this work, sol–gel modified technique is used to synthesize the (1-x)BTFO-(x)LSMO composites (x = 0, 0.1, 0.2, 0.3, and 0.4). The composite's dual (BTFO and LSMO) phases are verified using X-ray diffraction analysis. A scanning and transmission electron microscope is used to analyze the distinct morphology of the two phases that demonstrated the plate-like grains and quasi-spherical particles of BTFO and LSMO phases in the composites, respectively. The magnetic studies reveal that the saturation magnetization (Ms ∼ 7.0 emu/g) and coercive field (Hc ∼ 1660 Oe) increased by nearly-three and 66 times for 40 % LSMO contained composite. The enhanced magnetic behavior is due to the interaction between the multiple magnetic ordering (AFM/FM) present in the prepared composites. The estimated values of squareness ratio (Mr/Ms) are lower than 0.5, illustrating the multi-domain nature of the composites. The switching field distribution (SFD) plot indicates that strong exchange coupling exists in the x = 0.4 composite compared to others. The change in dielectric permittivity at different magnetic fields is due to the magnetodielectric (MD) coupling in the composites. The field-dependent MD studies reveal that maximum MD strength (∼0.34 %) and minimum magnetoloss (ML) (∼0.02 %) are observed in x = 0.2 and 0.1 composites at 100 kHz, respectively. It is due to the non-collinear alignment of magnetic Mn ions at RT, which leads to the inverse Dzyalonskii-Moriya interaction. Additionally, the maximum MD coupling strength γ (-16.87 (emu/g)2) is observed in the x = 0.2 composite. The observed MD response in the composites is due to the dominating grain capacitive effect rather than the resistive effect, which is ascertained by the frequency-dependent magnetoresistance measurement. Hence, the composite's enhanced magnetic and magnetodielectric behavior makes it a suitable candidate for multifunctional device applications.