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Magnetoelectric (ME) multiferroic composites are more promising candidates for low-power consumption devices, next-generation spintronic devices, and multistate memory devices since they exhibit significantly higher Magnetoelectric interaction over single-phase multiferroics. In this regard magnetic behaviour, dielectric, and magnetoelectric characteristics of a novel Pb-free (1-x) Na 0.5 Bi 0.5 TiO 3 -(x) Ni 0.5 Co 0.5 Fe 2 O 4 , (x = 0, 0.2, 0.4, 0.6, 0.8 & 1) particulate composites were explored. Solid-state synthesis was adopted to prepare the single-phase Na 0.5 Bi 0.5 TiO 3 (NBT), Ni 0.5 Co 0.5 Fe 2 O 4 (NCFO), and their composites. The presence of rhombohedral NBT and cubic inverse spinel NCFO in the composites were confirmed with X-ray diffraction (XRD) patterns. Microstrain (ε) induced in the prepared samples was estimated by using the Williamson-Hall (W-H) method. The piezoelectric NBT phase shows the tensile strain and the ferromagnetic NCFO shows the comprehensive strain. Among all the composites 0.8NBT-0.2NCFO shows a higher strain value of 0.012%, and the decrement in the strain values was observed upon increases in ferrite concentration. Backscattered scanning electron microscope (BS-SEM) images revealed the existence of highly dense uniformly distributed elements and Energy dispersive spectroscopy (EDS) confirmed the existing elements in the composites. UV–vis absorbance spectra disclosed a rise in energy gap values from 1.14 eV to 3.0 eV with increasing NBT percentage. Variations of dielectric permittivity and dielectric loss with respect to AC frequency were studied at room temperature (RT), and the 0.2NBT-0.8NCFO sample shows a high dielectric permittivity of 8500 at ∼100Hz. M − H (Magnetization-Magnetic field) hysteresis loops demonstrate the pure ferrite phase has a coercive field (H c) = 578 Oe, remnant magnetization (M r) = 21.43 emu/g and saturation magnetization (M s) = 71.29 emu/g. The M s and M r values in the composites are enhanced with increasing ferrite percentage. Studies on ME behaviour of (1-x) NBT-(x) NCFO, (x = 0.2,0.4,0.6 & 0.8) show the coupling effect between both the phases at room temperature and the highest coupling coefficient value 3.16mV/Cm. Oe was observed for the 0.8NBT-0.2NCFO further the reasons and mechanisms are discussed. [Display omitted] [ABSTRACT FROM AUTHOR]

Colossal Magneto Resistance (CMR) materials with the compositional formula, La 0.67 − x Eu x Sr 0.33 MnO 3 (where x = 0.3 , 0.33 , 0.36 and 0.39 ) were prepared by the sol–gel method. After characterizing the samples structurally, a systematic investigation of magnetization has been undertaken, over a temperature range 70–300 K under 0.05 T magnetic field. An effort has been made to calculate the magnetocaloric behavior of all the samples theoretically using the experimental magnetization data. Magnetocaloric effect parameters such as maximum entropy change, full width at half-maximum and relative cooling power under 0.05 T were computed. The observed behavior has been explained qualitatively. [ABSTRACT FROM AUTHOR]

Electronic band structure, ferroelectric and ferromagnetic properties of Cubic, Tetragonal and Rhombohedral (hexagonal axis) phases of multiferroic BiFeO 3 compound has been investigated using first-principles calculations under the generalized gradient (GGA) and TB-mBJ semi local (Tran-Blaha modified Becke-Johnson) potential approximations using WIEN2k code. For this purpose, the total energies were calculated as a function of reduced volumes and the data were fitted to Brich Murnaghan equation. The estimated ground state parameters are found to be comparable with those of experimental ones. The semiconducting behavior of the material was obtained using TB-mBJ method in the spin polarized mode. Analysis of the density of states indicates that the valence band consists of Fe-d and O-p states, while the conduction band is composed of Fe-d and Bi-p states. The analysis of electron localization function shows that stereochemically active lone-pair electrons are present at Bi sites of Rhombohedral and Tetragonal phases and are responsible for the displacements of Bi atoms from the centro-symmetric to the non-centrosymmetric structure leading to the exhibition of ferroelectricity. Further, it has been concluded that the “lone pair” may have been formed due to the hybridization of 6s and 6p atomic orbitals with 6s 2 electrons filling one of the resulting orbitals in Bi. The Polarization and the magnetic properties including susceptibility were obtained. The calculated magnetic moments at the iron sites are not integer values, since Fe electrons have a hybridization interaction with the neighboring O ions. [ABSTRACT FROM AUTHOR]