Vol.:(0123456789) 1 3 Journal of Materials Science: Materials in Electronics https://doi.org/10.1007/s10854-019-01194-3 Investigation on the optical, electrical, dielectric, and magnetic properties of (1−x)La 0.7 Ca 0.3 MnO 3 /xCoFe 2 O 4 nanocomposites Bandana Panda 1  · Krutika Lokapriya Routray 1  · Subrata Karmakar 1  · Dhrubananda Behera 1 Received: 15 January 2019 / Accepted: 20 March 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract (1−x)La 0.7 Ca 0.3 MnO 3 /xCoFe 2 O 4 (x = 0, 0.1, 0.3) nanocomposites are fabricated by glycine-nitrate method. XRD patterns and FTIR spectra confrm the phase formation of the nanocomposite. FESEM images divulge a reduction in the average particle size with enhanced incorporation of CoFe 2 O 4 . The band gap increases moderately followed by a blue shift in UV–Vis absorp- tion peaks. Frequency-dependent impedance and dielectric properties are investigated at and above the room temperature. The impedance of the system gets enhanced while the conductivity reduces accordingly. Nyquist plot of impedance displays the contribution of diverse nanostructures on the electrical property using R(Q g R g )(Q gb R gb ) circuit. Two types of conduction mechanism are observed in the studied system. The conduction in the low frequency regime is associated with correlated barrier hopping type conduction mechanism and in the high frequency regime is associated with overlapped large polaron tunneling conduction mechanism. The dielectric constant and tangent loss both are reduced on the incorporation of CoFe 2 O 4 . Comparatively low tangent loss value for x = 0.3 refects suitability in high-frequency device applications. The saturation magnetization M s and squareness ratio S is also high for x = 0.3 that is valuable for possible use of the (1−x)La 0.7 Ca 0.3 MnO 3 / xCoFe 2 O 4 nanocomposites in memory devices. 1 Introduction Nanocomposites have grabbed special attention of the researchers for their enhanced electric, dielectric and mag- netic properties. When the grain size reaches nanoscale, various quantum efects come into play governing variation in energy states and electronic structure; as a result, physi- cal properties of the system get modifed [1–3]. Manganite- ferrite nanocomposites are a captivating aspirant due to the presence of cross-correlated magnetic and electric property. This property can be jingled by varying the concentration of individual phases in the nanocomposite system. In the fabrication of the tunable nanocomposites, two things play a crucial role; one is a homogeneous mixing of individual phases and another is growing of individual nanoparticles in the neighboring environment. The ubiquity of both fer- romagnetic–ferroelectric couplings between two phases is a portal for the new magnetoelectric composite of extended applications [4–6]. Perovskite La 0.7 Ca 0.3 MnO 3 (LCMO) is an interesting compound in the group of hole-doped manganites. It pos- sesses ferromagnetic half-metallic behavior below its Curie temperature Tc (~ 260 K) and exhibits Colossal Magneto Resistance (CMR). The double exchange interaction among the manganese valence states Mn 3+ –O 2− –Mn 4+ leads to these novel properties [7]. These properties enable it to be used as cathode material in solid oxide fuel cells, data stor- age devices, the working substance in magnetic refrigera- tors, video tape recorders, magnetic sensors and spintronic devices etc. [8–10]. Electron hopping in this manganite is caused by MnO 6 octahedrons present in the unit cell. Con- tinuous charge transfer among Mn 3+→ Mn 4+ ions empowers it to behave as a dielectric material [11]. Above the Curie point, the system undergoes a second order phase transi- tion to a paramagnetic insulating state. Respectively, at and above the room temperature, it is a paramagnetic insula- tor [12–14]. Its optical, dielectric and magnetic properties can be enhanced by making nanocomposite with ferrites. Among ferrites, spinel CoFe 2 O 4 (CFO) seeks attention due to multifunctional behavior such as unique optical, dielec- tric, and magnetic properties. In CFO nanoparticles, Fe 3+ ions occupied both the tetrahedral and octahedral sites in unit cell. Most of the Co 2+ ions occupied the octahedral * Dhrubananda Behera dhrubananda_behera@yahoo.co.in 1 Department of Physics and Astronomy, National Institute of Technology, Rourkela, Rourkela, Odisha 769008, India