Recent Progress in Flexible Multiferroics

A great deal of interest has grown in both academia and industry toward flexible multiferroics in the recent years. The coupling of ferromagnetic properties with ferroelectric properties in multiferroic materials opens up many opportunities in applications such as magnetoelectric random access memories, magnetic field sensors, and energy harvesters. Multiferroic materials on a flexible platform bring an exciting opportunity for the next generation of consumer electronics owing to their unique characteristics of wearability, portability, and weight reduction. However, the fabrication of flexible multiferroic devices is still a great challenge due to various technical difficulties, including the requirement of high growth temperature of the oxide-based multiferroic materials, their lattice mismatch with the flexible substrates, and the brittleness of the functional layers. In this review article, we will discuss different methods of fabricating flexible or even freestanding oxide films to achieve flexible electronics. This article will address the benefits and challenges of each synthesis method in terms of interlayer interactions and growth parameters. Furthermore, the article will include an account of the possible bending limits of different flexible substrates without degrading the properties of the functional layer. Finally, we will address the challenges, opportunities, and future research directions in flexible multiferroics.

Tunable Magnetoelectric Coupling and Electrical Features in an Ultrathin Cr2Si2Te6 / In2Se3 Heterostructure

Two-dimensional (2D) van der Waals (vdW) heterostructures based on multiferroic materials have potential applications in novel low-dimensional spintronic devices. In this work, we have investigated a strong magnetoelectric coupling and...

Solid-State Heating Using the Multicaloric Effect in Multiferroics

The multicaloric effect is defined as the adiabatic reversible temperature change in multiferroic materials induced by the application of an external electric or magnetic field, and it was first theoretically proposed in 2012. The multicaloric effects in multiferroics, as well as other similar caloric effects in single ferroics, such as magnetocaloric, elastocaloric, barocaloric, and electrocaloric, have been the focus of much research due to their potential commercialization in solid-state refrigeration. In this short communication article, we examine the thermodynamics of the multicaloric effect for solid-state heating applications. A possible thermodynamic multicaloric heating cycle is proposed and then implemented to estimate the solid-state heating effect for a known electrocaloric system. This work offers a path to implementing caloric and multicaloric effects to efficient heating systems, and we offer a theoretical estimate of the upper limit of the temperature change achievable in a multicaloric cooling or heating effect.

Functional Polymer Composites Using Multiferroic Ceramic Nanofillers

Multiferroic materials exhibited more than one ferroic properties of piezoelectric, magnetostrictive, and magnetoelectric. Among the multiferroic materials, magnetoelectric (ME) materials coexisting ferroelectric and ferromagnetic properties has attracted great attention due to its unique applications such as energy harvesters, highly-sensitive magnetic sensors, actuators, memory devices. With the increase in demand of flexible and multifunctional electronic devices, polymer-based ME composites consisting of ferroelectric polymer matrix and ferromagnetic ceramic nanofillers have been developed by optimization of materials, structure, and process. In this review, we described research history and feasible applications for the polymer-based ME composites. We believe that the polymer-based ME composites can be a potential candidate for self-powered energy and sensing devices relevant to the fourth industrial revolution in the near future.

Magnetoelectric Coupling on the Fused Azulene Oligomers

<div><div><div><p>The global magnetic phase diagram for fused azulene oligomers is obtained by using a fermionic Hubbard Hamiltonian, a intermediate model between the molecular (Pariser-Parr-Pople empiric Hamiltonian) and spin-1/2 antiferromagnetic Heisenberg approaches. As a function of the on-site coulomb repulsion and the oligomer size we show that fused azulene transitions from a singlet (S = 0) to a higher-spin (S = 1, 2, 3) ground state. Near the quantum magnetic phase transition the electric dipole moment, present on fused azulene molecules, couples with the magnetic moment leading to a divergent magnetoelectric susceptibility at the boundary lines of the magnetic phase diagram. These spontaneous electric and magnetic polarizations, together with the magnetoelectric coupling between them, indicate that fuzed azulene molecules are potentially strong candidates for purely organic multiferroic materials.</p></div></div></div>

Magnetoelectric Coupling on the Fused Azulene Oligomers

<div><div><div><p>The global magnetic phase diagram for fused azulene oligomers is obtained by using a fermionic Hubbard Hamiltonian, a intermediate model between the molecular (Pariser-Parr-Pople empiric Hamiltonian) and spin-1/2 antiferromagnetic Heisenberg approaches. As a function of the on-site coulomb repulsion and the oligomer size we show that fused azulene transitions from a singlet (S = 0) to a higher-spin (S = 1, 2, 3) ground state. Near the quantum magnetic phase transition the electric dipole moment, present on fused azulene molecules, couples with the magnetic moment leading to a divergent magnetoelectric susceptibility at the boundary lines of the magnetic phase diagram. These spontaneous electric and magnetic polarizations, together with the magnetoelectric coupling between them, indicate that fuzed azulene molecules are potentially strong candidates for purely organic multiferroic materials.</p></div></div></div>

MAGNETOELECTRIC COUPLING MEASUREMENT TECHNIQUES IN MULTIFERROIC MATERIALS

Magnetoelectric multiferroics are solid-state materials which exhibit a coupling between ferroelectric and magnetic orders. This phenomenon is known as the magnetoelectric (ME) effect. Multiferroic materials possess a wide range of potential applications in such fields as metrology, electronics, energy harvesting & conversion, and medicine. Multiferroic research is facing two main challenges. Firstly, scientists are continuously trying to obtain a material with sufficiently strong, room-temperature ME coupling that would enable its commercial application. Secondly, the measurement techniques used in multiferroic research are often problematic to implement in a laboratory setting and fail to yield reproducible results. The aim of the present work is to discuss three most commonly used methods in multiferroic studies; the lock-in technique, the Sawyer-Tower (S-T) circuit and dielectric constant measurements. The paper opens with a general description of multiferroics which is followed by mathematical representation of the ME effect. The main body deals with the description of the aforementioned measurement techniques. The article closes with a conclusion and outlook for future research.