Investigations on low temperature magnetic and magnetoelectric properties of multiferroic-NiO nanocomposites

Multiferroic BiFeO3-NiO (BFO-NiO) nanocomposites have been synthesized using sol-gel route and investigated via. the first principle DFT calculations, multiferroic-magnetoelectric response, and extremely low-temperature magnetic analysis. Powder X-ray diffraction (XRD) patterns along with Rietveld refinement data confirmed the phase purity viz. rhombohedral distorted perovskite BiFeO3- rock salt type NiO crystal structure and composite formation. Temperature dependent magnetic measurements confirmed the enhancement in the magnetism and the exchange bias effect due to the antiferromagnetic (AFM) and ferromagnetic (FM) exchange coupling in-teractions. Zero field cooled (ZFC) and field cooled (FC) magnetic results demonstrate the observation of typical superparamagnetic (SP) behavior for all the samples at room temperature whereas at low temperature a tran-sition is reported from SP to quantum superparamagnetic (QSP) state through quantum tunneling of magnetic moment for all samples. Maximum polarization of 5.7 & mu;C/cm2 is observed for BFO-20% NiO composition. The noticeable change in the ferroelectric P vs E loops in the presence of external magnetic field confirm the evidence of multiferroic and magnetoelectric coupling behavior in the BFO-NiO nanocomposites. The DFT calculations have been done using WIEN2k software and found in well agreement with the reported experimental results. Further, the suitable temperature dependent magnetic squareness, evidence of considerable magnetoelectric coupling, exchange bias effect and SP nature make the BFO-NiO nanocomposites considerable suitable for various device applications such as information storage, magnetic random access memory, targeted drug de-livery, magnetic resonance imaging (MRI), bio-sensing and tailoring other photocatalytic applications.

Automated summary

Multiferroic BiFeO3-NiO (BFO-NiO) nanocomposites were synthesized using sol-gel route and characterized for their multiferroic-magnetoelectric properties. The composite exhibited enhanced magnetism and exchange bias effect due to the interactions between antiferromagnetic and ferromagnetic exchange couplings. The temperature-dependent magnetic measurements showed a transition from superparamagnetic behavior to quantum superparamagnetic state at low temperature. The nanocomposites demonstrated considerable suitable for various device applications such as information storage, magnetic random access memory, and bio-sensing.