Multiferroic magnetoelectric composite systems such as ferromagnetic-ferroelectric heterostructures have recently attracted an ever-increasing interest and provoked a great number of research activities, driven by profound physics from coupling between ferroelectric and magnetic orders, as well as potential applications in novel multifunctional devices, such as sensors, transducers, memories, and spintronics. In this Review, we try to summarize what remarkable progress in multiferroic magnetoelectric composite systems has been achieved in most recent few years, with emphasis on thin films; and to describe unsolved issues and new device applications which can be controlled both electrically and magnetically.

Recent Progress in Multiferroic Magnetoelectric Composites: from Bulk to Thin Films

An insight into the analogies, state-of-the-art technologies, concepts, and prospects under the umbrella of perovskite materials (both inorganic-organic hybrid halide perovskites and ferroelectric perovskites) for future multifunctional energy conversion and storage devices is provided. Often, these are considered entirely different branches of research; however, considering them simultaneously and holistically can provide several new opportunities. Recent advancements have highlighted the potential of hybrid perovskites for high-efficiency solar cells. The intrinsic polar properties of these materials, including the potential for ferroelectricity, provide additional possibilities for simultaneously exploiting several energy conversion mechanisms such as the piezoelectric, pyroelectric, and thermoelectric effect and electrical energy storage. The presence of these phenomena can support the performance of perovskite solar cells. The energy conversion using these effects (piezo-, pyro-, and thermoelectric effect) can also be enhanced by a change in the light intensity. Thus, there lies a range of possibilities for tuning the structural, electronic, optical, and magnetic properties of perovskites to simultaneously harvest energy using more than one mechanism to realize an improved efficiency. This requires a basic understanding of concepts, mechanisms, corresponding material properties, and the underlying physics involved with these effects.

Mutual Insight on Ferroelectrics and Hybrid Halide Perovskites: A Platform for Future Multifunctional Energy Conversion.

Magnetocaloric effect: From materials research to refrigeration devices

A2B′B″O6 perovskites: A review

Electrocaloric materials for future solid-state refrigeration technologies

Synthesis and characterizations of microwave sintered ferrite powders and their composite films for practical applications

The dielectric property and the electronic structure of a double perovskite, Sr2FeSbO6 (SFS) synthesized by solid state reaction technique are investigated The x-ray diffraction of the sample taken at room temperature shows cubic phase The scanning electron micrograph of the sample also confirms the formation of the single phase of the material We have measured the capacitance and conductance of SFS in a frequency range from 50 Hz to 1 MHz and in a temperature range from 163 to 463 K A relaxation is observed in the entire temperature range as a gradual decrease in ϵ′(ω) and as a broad peak in ϵ″(ω) The frequency dependent electrical data are analyzed in the framework of conductivity and electric modulus formalisms The frequencies corresponding to the maxima of the imaginary electric modulus at various temperatures are found to obey an Arrhenius law with an activation energy of 074 eV The Cole–Cole model is used to study the dielectric relaxation of SFS The scaling behavior of imaginary part of el

Dielectric relaxation and electronic structure of double perovskite Sr2FeSbO6

In this work, the investigation of magnetic proximity effect was extended to Ta which has been reported to have a negative spin Hall angle. Magnetoresistance (MR) and Hall measurements for in-plane and out-of-plane applied magnetic field sweeps were carried out at room temperature. The size of the MR ratio observed (∼10−5) and its magnetization direction dependence are similar to that reported in Pt/yttrium iron garnet, both of which can be explained by the spin Hall magnetoresistance theory. Additionally, a flip of magnetoresistance polarity is observed at 4 K in the temperature dependent measurements, which can be explained by the magnetic proximity effect induced anisotropic magnetoresistance at low temperature. Our findings suggest that both magnetic proximity effect and spin Hall magnetoresistance have contribution to the recently observed unconventional magnetoresistance effect.

Investigation of magnetic proximity effect in Ta/YIG bilayer Hall bar structure

Synthesis and electromagnetic properties of U-type hexaferrites Ba4B2Fe36O60 (B: Co, Ni, Cu)

A systematic study on the structural, magnetic, and transport properties of an all-oxide granular system consisting of Fe3O4 grains dispersed in an insulating Al2O3 matrix is presented. X-ray diffraction and transmission electron microscopy analyses provide the structure of nanosized Fe3O4 grains embedded in an amorphous Al2O3 matrix and confirm that the Fe3O4 grain size decreases with increasing Al2O3 volume fraction x. Magnetic measurements further show that the coercivity of the granular films decreases with increasing x due to decreasing Fe3O4 grain size, with the magnetization curves exhibiting typical superparamagnetic characteristics for x0.19. Temperature dependence of resistance and nonlinearity in current-voltage characteristics confirms that the spin dependent tunneling of conduction electrons across grains dominates the transport properties. This tunneling conductance depends on the relative orientation of magnetization between Fe3O4 grains, which results in an isotropic granular tunneling magnetoresistance TMR effect. We also observed that the granular TMR ratio has strong temperature dependence and decreases with increasing temperature for all the granular films.

https://www.ece.nus.edu.sg/stfpage/eleaao/Adekunle_Adeyeye/funcmat/funcmat1.pdf

Santiranjan Shannigrahi

Papers

Synthesis and characterizations of microwave sintered ferrite powders and their composite films for practical applications

Dielectric relaxation and electronic structure of double perovskite Sr2FeSbO6

Investigation of magnetic proximity effect in Ta/YIG bilayer Hall bar structure

Synthesis and electromagnetic properties of U-type hexaferrites Ba4B2Fe36O60 (B: Co, Ni, Cu)

Magnetic and tunneling magnetoresistive properties of an all-oxide Fe 3 O 4 -Al 2 O 3 granular system