Recent developments related to multifunctional ferroelectric for room-temperature applications

Abstract

Ferroelectric materials are good candidates for coupling properties of other functions, such as mechanical, superconductivity, and magnetism. Recent publications have reported important approaches of bulk and nanostructure ferroelectric materials at room temperature [1][2][3][4][5] Magnetoelectric multiferroic materials enable fast electrical writing and magnetic reading, and can thus be applied to non-volatile random access memory. However, fast electrical writing and magnetic reading exist more difficulties in single crystalline structure bulk materials because ferroelectricity need closed-shell d 0 or s 2 cation and ferromagnetic need open-shell d n with unpaired electron. Although previous works have reported composite multiferroics at room temperature by multiphase mixtures of magnetic and ferroelectric materials [6], the magnetoelectric coupling effect will prevent complete switch of ferroelectricity. In a recent issue of Nature, researchers at the University of Liverpool, Trinity College Dublin, and West Virginia University reported tunable multiferroic materials at room temperature in a bulk perovskite oxide [1]. The authors constructed a percolating network of magnetic ions with strong superexchange interactions, and this network has a structural scaffold with polar lattice symmetries at a morphotropic phase boundary. This strategy overcomes synthesizing difficulties for tunable multiferroic materials and provides a new direction for applications in low-power and high-density information storage.Ferroelectric can be coupled to other functional properties. For example, the conduction, dielectric, and magnetic properties of ferroelectrics can be changed by strain. Theoretical works have predicted that alkaline-earth manganites that have the perovskite structure with larger-than-equilibrium lattice parameters exhibit ferroelectricity. For bulk SrMnO 3 , ferroelectricity is verified by partially replacing Sr with Ba. Density functional theory (DFT) calculations predicted that epitaxial SrMnO 3 films will exhibit polarization under >1% epitaxial tensile strain. Researchers in Switzerland and Spain reported that strain increases the concentration of oxygen vacancies, which couple to the polar domain walls in SrMnO 3 thin films (thickness of 20 nm) [2]. By DFT calculations and experimental measurements, they found that the local structures conducting polar nanodomains at room-temperature are embedded in insulating domain boundaries, which can form "nanocapacitor" domains. The stable capacitance offers "nanobits," which have potential applications in high-density information storage at room temperature.Ferroelectric materials have important nanoelectronic applications at room temperature [3]. Many researchers have demonstrated that nanostructures will enhance the performance of nanodevices [2][3][4]. However, it is a longstanding notion that ferroelectricity will fade in a few nanometers scale [3]. Previous studies developed several strategies to overcome the low dimension difficulties of ferroelectricity have ...

Applications of ferroelectrics in photovoltaic devices

“…The hysteresis curve that is obtained when P is plotted vs. E is very similar to the hysteresis loop of a typical ferromagnetic material. Ferroelectrics owe their name to this similarity with ferromagnetic materials [5]. Some ferroelectrics exhibit spontaneous electrical polarization in a certain range of temperatures.…”