Magnetoelectric coupling at the NiFe2O4/PZT (001) interface: A density functional theory investigation

International audienceMagnetoelectric (ME) coupling at the Ferrimagnetic/Ferroelectric NiFe2O4/PbZr0.5Ti0.5O3(001) (NFO/PZT) heterostructure have been investigated using first-principles within density-functional theory in the framework of GGA + U. The (Zr0.5Ti0.5)O-2-terminated and PbO-terminated PZT surfaces are considered at the NiFe2O4/PZT interface (NFO/ZTO and NFO/PbO). Based on the interfacial separation work; our first-principle calculations predict that the (Zr0.5Ti0.5)O-2-terminated PZT surfaces is energetically more favorable than the PbO-terminated PZT surfaces at the NiFe2O4/PZT interface. Moreover, it is found that the magnetoelectric coupling in this system arises from the interface bonding and the electronic origin of the large magnetoelectric coupling at NFO/ZTO interface is due to the hybridizations of orbitals of interface Ni, Fe, T, Zr, O atoms. In addition, the maximum magnetoelectric coefficient of alpha = 3.15 x 10(-10) G.cm/V has been achieved for (Zr0.5Ti0.5)O-2-terminated PZT surfaces in NiFe2O4/PZT interface

Prediction of Magnetoelectric Properties of Defect BiFeO3 Thin Films Using Monte Carlo Simulations

Magnetoelectric materials have received astonishing attention due to their great potential for nanotechnology and magnetoelectric applications. Herein, the ferroelectric, magnetic and magnetoelectric properties of multiferroic BiFeO3 (BFO) thin films have been carried out using Monte Carlo simulation investigations in the framework of the Heisenberg model. Exchange coupling interactions in magnetic and ferroelectric sublattices that correspond to the experimental critical temperature were estimated. Temperature dependence of the internal energy, specific heat, magnetization, electric polarization and their susceptibilities in BFO thin films have been systematically analyzed. Moreover, the effect of magnetoelectric coupling interaction Jme on M-H and P-H hysteresis loops and magnetoelectric voltage coefficient were studied. A large magnetoelectric voltage coefficient of 104 mV/(cm.Oe) was predicted in BFO thin films with 25% defects. Furthermore, the defect mechanism can be used to control the polarization switching by the magnetic field in BFO system. The obtained results highlight the large magnetoelectric effect in BFO multiferroic thin films for multifunctional magnetoelectric devices. \textcopyright 2021 Elsevier B.V

Tunable maximum energy product in CoFe2O4 nanopowder for permanent magnet application

In this study, we report the behavior of maximum energy product (BH)max of cobalt ferrite nanopowder towards the variation of calcinations temperature. The studied CoFe2O4 nanopowder was synthesized using sol–gel autocombustion method. X-ray diffraction, scanning electron microscopy, Mössbauer spectroscopy and superconducting quantum interference device magnetometer techniques were used to characterize crystal structure, phase composition, morphology and magnetic properties. By changing the calcination temperature (T = 600 °C, 800 °C, 1000 °C and 1100 °C), the structural and magnetic properties of the compounds could be tuned. The magnetic properties results show that the highest value of (BH)max is close to 0.35 MGOe observed for the sample calcined at T = 800 °C. These results suggest that (BH)max of cobalt ferrite nanopowder can be enhanced by optimizing synthesis steps

Modelling of the ferroelectric and energy storage properties of PbZr1-xTixO3 thin films using Monte Carlo simulation

International audienceA Monte Carlo model was developed to study the ferroelectric and energy storage properties of PbZr1-xTixO3 (PZT). The proposed model aims to calculate the exchange coupling constants in ferroelectric PbZr1-xTixO3 thin films system, useful for Monte Carlo simulation within metropolis algorithm. Thus, the effect of temperature on the ferroelectric properties of the PZT thin films, such as, hysteresis loops, polarization and coercive field were investigated. Moreover, the phase diagram as a function of x values of T-i in PbZr1-xTixO3 was studied. The obtained P-E hysteresis loops permitted to predicte the energy storage properties of the studied system. A maximum of the recoverable energy density of 13.93 J cm(-3) was obtained with the energy density efficiency of 79% for x = 0. The obtained results are in good agreement with the reported experimental data for the same material

Prediction of Magnetoelectric Properties of Defect BiFeO3 Thin Films Using Monte Carlo Simulations

International audienceMagnetoelectric materials have received astonishing attention due to their great potential for nanotechnology and magnetoelectric applications. Herein, the ferroelectric, magnetic and magnetoelectric properties of multiferroic BiFeO3 (BFO) thin films have been carried out using Monte Carlo simulation investigations in the framework of the Heisenberg model. Exchange coupling interactions in magnetic and ferroelectric sublattices that correspond to the experimental critical temperature were estimated. Temperature dependence of the internal energy, specific heat, magnetization, electric polarization and their susceptibilities in BFO thin films have been systematically analyzed. Moreover, the effect of magnetoelectric coupling interaction Jme on M-H and P-H hysteresis loops and magnetoelectric voltage coefficient were studied. A large magnetoelectric voltage coefficient of 104 mV/(cm.Oe) was predicted in BFO thin films with 25% defects. Furthermore, the defect mechanism can be used to control the polarization switching by the magnetic field in BFO system. The obtained results highlight the large magnetoelectric effect in BFO multiferroic thin films for multifunctional magnetoelectric devices. \textcopyright 2021 Elsevier B.V

Influence of synthesis methods with low annealing temperature on the structural and magnetic properties of CoFe2O4 nanopowders for permanent magnet application

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