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Ferroic Materials and Devices for Flexible Memory
Published in Muhammad Mustafa Hussain, Nazek El-Atab, Handbook of Flexible and Stretchable Electronics, 2019
Saidur R. Bakaul, Mahnaz Islam, Md. Kawsar Alam
Ferroic materials exhibit two or more stable states in the absence of an electric, magnetic, or mechanical force. These states are typically energetically degenerate and separated by an energy barrier, which can be overcome by any or a combination of these forces. Based on the conjugate forces, ferroic materials are generally classified in three categories: ferromagnetic (FM), ferroelectric (FE), and ferroelastic (FS). FM and FE memories depend on the properties of electrons, namely, spin and charge, respectively, whereas FS memories rely on the asymmetry in the internal strain of a material and the associated mechanical energy. The common modalities among the three materials types are a hysteretic dependence of the order parameter on the conjugate force and a temperature-dependent phase transition between the para and ferro states. The hysteresis and the tendency of remembering the previously applied stimulus have made these materials candidates to be memory materials.
Domain Walls in Multiferroic Materials and Their Functional Properties
Published in Tamalika Banerjee, Oxide Spintronics, 2019
Ferroics are materials that display spontaneous ordering of a physical quantity below a certain temperature, the so-called Curie temperature, TC, or, in general, ordering temperature, To. Three types of ferroic materials have been known for a long time: “ferroelectrics” present spontaneous polarization, “ferromagnets” show spontaneous magnetization and “ferroelastics” display spontaneous strain. Thermodynamically, these are the complementary variables of the ordering electric, magnetic, and strain fields, respectively. The most interesting behavior takes place when the appearance of spontaneous polarization, magnetization or strain is associated with the loss of one or more symmetry elements while keeping some others unaffected, that is, when the transition takes place in between two phases that are related by symmetry by a group-subgroup relationship. Then, within the Landau approach, the emergent physical properties are called the order parameters of the ferroelectric, ferromagnetic, or ferroelastic phase transition, respectively. Ferroics can be also classified by their response under time and spatial reversal, as presented in Fig. 5.1. The essential and distinct characteristic of a ferroic material is the formation of domains, or regions with different orientations of the order parameter, which will be discussed in more details in Section 5.3.
Layered Two-Phase Magnetoelectric Materials
Published in Sam Zhang, Dongliang Zhao, Advances in Magnetic Materials, 2017
Zhaofu Du, Sam Zhang, Dongliang Zhao, Tat Joo Teo, Rajdeep Singh Rawat
Traditionally, ferroic properties include ferroelectricity, ferromagnetism, and ferroelasticity. However, current practice tends to exclude ferroelasticity but encompasses ferrotoroidicity (i.e., an ordered arrangement of magnetic vortices) and even antiferroicity [1]. Multiferroic materials are materials that exhibit more than one primary ferroic property in a single material. Figure 6.1 illustrates ferroic properties of multiferroic materials.
Elastic and attenuation behavior of the Bi1-x Re x FeO3 (x = 0 & 0.1; Re = La, Pr, Nd & Sm) multiferroic system
Published in Phase Transitions, 2021
Elle Sagar, K. Vijaya Kumar, P. Venugopal Reddy
The materials possessing at least two out of the three well-known ferroic orders viz., ferroelectric, ferromagnetic or ferroelastic are called multiferroics. Due to their potential applications, such as information storage devices, electronic devices and sensors in a variety of multifunctional devices, these materials have drawn the attention of the scientific community. The magnetic or electric fields can manipulate both spin and charge, which will be allowed by the interaction between the magnetic and electronic degrees of freedom [1,2]. Among the family of multiferroic materials, BiFeO3 (BFO), with a distorted perovskite (ABO3) and rhombohedral crystal structure with R-3c space group, has attracted the attention of researchers due to its ability to exhibit both ferromagnetic (G-type antiferromagnetic) and ferroelectric properties above room temperature [3,4]. In fact, the bulk BFO shows multiferroic properties with high ferroelectric transition temperature (1100 K) and weak AFM Neel temperature (643 K) [5]. Due to the interesting properties and non-toxic nature of this multiferroic material, it can replace well-known PZT in ferroelectric memory applications.
Multiferroic and half-metallic character of hexagonal BaTi0.5Fe0.5O3: DFT based calculation
Published in Philosophical Magazine, 2023
Ayyoub Bezzalla, Mokhtar Elchikh, Nadia Iles
Ferroelectricity and ferromagnetism are among the most important properties used in the electronics industry [1–3]. The electronic structure of materials exhibiting both magnetic and ferroelectric properties is completely different. Therefore, it is rare to find an electronic structure that exhibits both magnetism and ferroelectricity. Materials that exhibit at least two of the ferroic orders, including ferroelectricity, ferromagnetism and ferroelasticity, are called ‘multiferroics’ [4]. H. Schmid introduced this term in 1994 [5]. The preparation and study of multiferroic transition-metal (TM) oxide-perovskites have been greatly developed for use in spintronics industry [6]. This class of compounds contains the most promising magnetic, ferroelectric and multiferroic materials such as BaTiO3 (BTO), (PbZr)TiO3 (PZT) and BiFeO3 [7]. Khomskii [7] asked the questions: why are ferroelectric and ferromagnetic phenomena mutually exclusive? Why this is so is an important and still not fully resolved question? The localised exchange interaction of magnetic moments determines the microscopic nature of magnetic order, while the microscopic mechanisms of ferroelectricity are not well understood in many cases. For this reason, the main problem in the study of multiferroic systems lies in the ferroelectric part [7]. The problem is that the ferroelectric TM perovskites have an empty shell (d levels); this is a necessary but not a sufficient condition for ferroelectricity. However, the magnetic TM perovskites have partially filled shells (d- or f-levels), which means that ferroelectric systems can never be ferromagnetic and vice versa [7]. Off-centre shifts of TM ions provide the main driving force for ferroelectricity [7].
Manifestation of ferroelastoelectric phase transition in temperature changes of the optical absorption edge in (NH4)2CuCl4·2H2O crystal
Published in Phase Transitions, 2022
V. Kapustianyk, S. Semak, Yu Chornii, M. Rudko
The search for new crystalline ferroics is an urgent task today since such materials are widely used in functional electronic devices, particularly in various sensors, modulators, converters, etc. [1,2]. The second-order ferroics, including ferroelastoelectrics, and the magnetic multiferroics, combining simultaneously magnetic and ferroelectric/ferroelastoelectric (FEE) types of orders is of special interest to scientists.