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

Effect of co-substitutions (Ca–Mn) on structural, electrical and magnetic characteristics of bismuth ferrite

The magnetodielectric response of a double perovskite oxide Lu2NiMnO6 (LNMO) synthesised by the sol–gel process has been investigated. The Rietveld refinement of the X-ray diffraction data indicates that the room-temperature crystal structure of LNMO is monoclinic with the space group P21/n, which contains an ordered array of alternate MnO6 and NiO6 octahedra. X-ray photoelectron spectroscopy studies confirm the mix valence state of Mn (4+ and 3+) and Ni (2+ and 3+). The optical band gap (Eg = 1.56 eV) obtained from the UV-Visible absorption spectrum suggests that LNMO is a semiconductor. The field cooled and zero-field cooled measurements show the ferromagnetic behaviour of the sample with the transition temperature (Tc) = 45 K and a saturation magnetization of 5.2 μB/f.u. is observed at 2.5 K. The temperature and frequency dependent dielectric measurements reveal colossal values of the dielectric constant, which are interpreted by the Maxwell-Wagner interfacial polarization. The temperature dependence of the bulk dc conductivity indicates a variable-range-hopping mechanism. The saturation polarization value is estimated to be 232 μC/m2 from the pyroelectric current measurement. A negative magnetodielectric effect of 1% is observed at the paramagnetic to ferromagnetic transition temperature. The electronic structure calculations based on density functional theory have been performed to analyse the magnetic properties of LNMO.

Magnetic ordering and conduction mechanism of different electroactive regions in Lu2NiMnO6

The frequency-dependent dielectric relaxation in barium–aluminium–niobate, BaAl1/2Nb1/2O3 (BAN), at low temperatures (103–443 K) is investigated by alternating-current impedance spectroscopy in the framework of conductivity and electric modulus formalisms. The Havriliak–Negami expression is used to analyse the electric modulus data. The scaling behaviour of the imaginary part of the electric modulus suggests that the relaxation describes the same mechanism at various temperatures. The frequency-dependent conductivity spectra follow the power law. The electronic structure of BAN is studied using x-ray photoemission spectroscopy (XPS). The XPS data are analysed by the first-principles full potential linearized augmented-plane-wave method using density functional theory under the generalized gradient approximation. The electronic structure calculation reveals that the electrical properties of BAN are dominated by the interaction between niobium d-states and oxygen p-states. The 27Al and 93Nb nuclear magnetic resonance (NMR) studies of the sample are performed at 78 and 73 MHz, respectively, in the temperature range 4–295 K to understand the transport properties of charge carriers in terms of their dynamics on a microscopic level. The description of the NMR lineshape is given on the basis of analytical formulae. The NMR investigation confirms the chemical ordering of 1:1 Al/Nb in BAN.

https://iopscience.iop.org/article/10.1088/0953-8984/20/44/445206/pdf

Dielectric relaxation and electronic structure of BaAl1/2Nb1/2O3: x-ray photoemission and nuclear magnetic resonance studies

The present invention provides a thin film photovoltaic device and a method of forming a thin film photovoltaic device. The thin film photovoltaic device has a substrate, a thin film layer formed on the substrate and first and second electrodes formed on one side of the thin film layer. By applying an electric field over the first and second electrodes, the thin film layer is polarized in a direction parallel to the surface plane of the film. Upon exposure to light, the thin film layer converts light energy into electricity. According to the method, a thin film layer is formed on a substrate. A first electrode and a second electrode are formed on one side of the thin film layer. By applying an electric field over the first and second electrodes, the thin film layer is polarized in a direction parallel to the surface plane of the film.

Santiranjan Shannigrahi

Papers

Effect of co-substitutions (Ca–Mn) on structural, electrical and magnetic characteristics of bismuth ferrite

Magnetic ordering and conduction mechanism of different electroactive regions in Lu2NiMnO6

Dielectric relaxation and electronic structure of BaAl1/2Nb1/2O3: x-ray photoemission and nuclear magnetic resonance studies

Thin film photovoltaic device

Erratum: “Thickness effects on photoinduced current in ferroelectric (Pb0.97La0.03)(Zr0.52Ti0.48)O3 thin films” [J. Appl. Phys. 101, 014104 (2007)]