We present a theory for surface polaritons on ferroelectric-antiferromagnetic materials with canted spin structure. Canting is assumed to be due to a Dzyaloshinkii-Moriya interaction with the electric polarisation and weak ferromagnetism directed in the plane parallel to the surface. Surface and bulk modes for a semi-infinite film are calculated for the case of transverse magnetic polarisation. Example results are presented using parameters appropriate for BaMnF4. We find that the magnetoelectric interaction gives rise to "leaky" surface modes, i.e. pseudosurface waves that exist in the pass band, and that dissipate energy into the bulk of material. We show that these psuedosurface mode frequencies and properties can be modified by temperature, and application of external electric or magnetic fields.
University of Jinan（济南大学）；Institute for Superconducting and Electronic Materials, Faculty of Engineering and Information Sciences, University of Wollongong（伍伦贡大学工程与信息科学学院超导与电子材料研究所）
We study the magnetoelectric and electrocaloric response of strain-engineered, multiferroic SrMnO$_3$, using a phenomenological Landau theory with all parameters obtained from \emph{first-principles}-based calculations. This allows to make realistic and materials-specific predictions about the magnitude of the corresponding effects. We find that in the vicinity of a tetracritical point, where magnetic and ferroelectric phase boundaries intersect, an electric field has a huge effect on the antiferromagnetic order, corresponding to a magnetoelectric response several orders of magnitude larger th…
Magnetic-Field-Dependent Raman Scattering in Multiferroic Bilayer Films: Evidence for Stress-Mediated Magnetoelectric Coupling
首次报道了Pb（Zr，Ti）O_3-CoFe_2 O_4双层多铁体系的磁场相关拉曼散射研究。纳米双层膜的声子频率随着磁场的变化而发生明显的变化，而单层Pb（Zr，Ti）O3膜则没有这种变化。CoFe 2 O 4层的磁致伸缩产生机械传递到Pb（Zr，Ti）O3层的应力，导致模式变化。观察到的磁场诱导软化的软模式的Pb（Zr，Ti）O3层承担着一个惊人的相似的直接磁电输出的双层，提供证据的应力介导的磁电耦合机制的多铁性双层。
The magnetoelectric effect and skyrmions are two fundamental phenomena in the field of condensed-matter physics. Here, using first-principles calculations and Monte-Carlo simulations, we propose that strong magnetoelectric coupling can be demonstrated in a multiferroic heterobilayer consisting of two-dimensional (2D) MnSTe and α-In2Se3. As the electric polarization in ferroelectric α-In2Se3 is switched, the creation and annihilation of topological magnetic phase can be achieved in this multiferroic heterobilayer, giving rise to the intriguing ferroelectrically controllable skyrmions. This feat…
Electric susceptibility of antiferromagnetic multiferroics with cycloidal spin order at magnetoelectric effect associated with collinear component of spins
Epitaxial growth of multiferroic Pb(Zr0.57Ti0.43)O3-Pb(Fe2/3W1/3)O3 solid-solution thin films and their magnetoelectric effects
本文报道了用脉冲激光沉积法外延生长单相[Pb（Zr 0.57 Ti 0.43）O3]0.8[Pb（Fe 2/3 W 1/3）O3]0.2（PZT-PFW）固溶体薄膜。X射线衍射测试表明薄膜具有四方晶系结构。该薄膜在室温下表现出铁电性和弱铁磁响应。磁电效应进行了研究，非线性磁电系数进行了测量，发现是可比的多铁性六方锰氧化物，但至少两个数量级小于多晶PZT-PFW薄膜。
Realizing topological magnetism and its electric control are intensive topics in the spintronics due to their promising applications in information storage and logic technologies. Here we unveil that both can be achieved in the two-dimensional (2D) magnetoelectric multiferroics. Using first-principles calculations, we show that strong Dzyaloshinskii-Moriya interaction (DMI), which is the key ingredient for the formation of exotic chiral magnetism, could be induced in 2D multiferroics with vertical electric polarization via Rashba effect. We verify that such significant DMI can promote sub-10 n…
In this article, we perform the symmetry analysis of perovskite-based multiferroics: bismuth ferrite (BiFeO3)-like, orthochromites (RCrO3), and Ruddlesden-Popper perovskites (Ca3Mn2O7-like), being the typical representatives of multiferroics of the trigonal, rhombic, and tetragonal crystal families and explore the effect of crystallographic distortions on magnetoelectric properties. We determine the principal order parameters for each of the considered structures and obtain their invariant combinations consistent with the particular symmetry. This approach allowed us to analyze the features of…
Magnetoelectric Phase Diagrams of Multiferroic GdMn2O5
研究了多铁性GdMn_2 O_5在外加磁场中的电磁性质，绘制了该材料的磁电相。由于强磁电耦合，介电常数对GdMn 2 O 5中的相界高度敏感，这允许构建场-温度相图。观察到几个相变是强烈的场依赖于相对于场的方向和强度。沿着晶体学a轴的磁场的相图很好地对应于由Gd磁矩的90度旋转引起的极化步骤。我们的结果支持两个铁电亚晶格，Mn-Mn和Gd-Mn与强R-Mn（4f-3d）相互作用的极化在RMn 2 O 5的模型。
Two-dimensional (2D) semiconducting multiferroics that can effectively couple magnetic and polarization (P) orders have great interest for both fundamental research and technological applications in nanoscale, which are, however, rare in nature. In this study, we propose a general mechanism to realize semiconducting 2D multiferroics via vdW heterojunction engineering, as demonstrated in a typical heterostructure consisting of magnetic bilayer CrI3 (bi-CrI3) and ferroelectric monolayer In2Se3. Interestingly, the novel indirect orbital coupling between Se 4p and Cr 3d orbitals, intermediated by …
Magnetoelectric training of multiferroic domains in Mn$_2$GeO$_4$
ETH Zurich（苏黎世联邦理工学院）；Loughborough University（拉夫堡大学）；Paul Scherrer Institut（保罗谢勒研究所）；High Energy Accelerator Research Organization (KEK)（高能加速器研究机构）；University of Tokyo（东京大学）；Norwegian University of Science and Technology (NTNU)（挪威科技大学）
The key physical property of multiferroic materials is the existence of a coupling between magnetism and polarization, i.e. magnetoelectricity. The origin and manifestations of magnetoelectricity can be very different in the available plethora of multiferroic systems, with multiple possible mechanisms hidden behind the phenomena. In this Review, we describe the fundamental physics that causes magnetoelectricity from a theoretical viewpoint. The present review will focus on the main stream physical mechanisms in both single phase multiferroics and magnetoelectric heterostructures. The most rece…
Nowdays, multiferroic materials with magnetoelectric coupling have many real-world applications in the fields of novel memory devices. It is challenging is to create multiferroic materials with strongly coupled ferroelectric and ferrimagnetic orderings at room temperature. The single crystal of ferric selenide (Fe3Se4) shows type-II multiferroic due to the coexistence of ferroelectric as well as magnetic ordering at room temperature. We have investigated the lattice instability, electronic structure, ferroelectric, ferrimagnetic ordering and transport properties of ferroelectric metal Fe3Se4. …
Multiferroic Properties of Electrospun CFO-BCTSn Nanocomposites for Magnetoelectric and Magnetic Field Sensing Applications
Jozef Stefan Institute（约瑟夫·斯蒂芬研究所）；University of Picardie Jules Verne（皮卡第朱尔斯·凡尔纳大学）；Cadi-Ayyad University, Faculty of Sciences and Technology（卡迪·阿亚德大学科学与技术学院）；University Mohammed VI Polytechnic (UM6P)（穆罕默德六世理工大学）；Aix-Marseille University - CNRS（艾克斯-马赛大学-法国国家科学研究中心）；Institute of Physics AS CR（捷克科学院物理研究所）
Clear anomalies in the lattice thermal expansion (deviation from linear variation) and elastic properties (softening of the sound velocity) at the antiferromagnetic-to-paramagnetic transition are observed in the prototypical multiferroic BiFeO3 using a combination of picosecond acoustic pump-probe and high-temperature X-ray diffraction experiments. Similar anomalies are also evidenced using first-principles calculations supporting our experimental findings. Those calculations in addition to a simple Landau-like model we also developed allow to understand the elastic softening and lattice chang…
Using THz spectroscopy, we show that the spin-wave spectrum of multiferroic BiFeO$_3$ in its high-field canted antiferromagnetic state is well described by a spin model that violates rhombohedral symmetry. We demonstrate that the monoclinic distortion of the canted antiferromagnetic state is induced by the single-ion magnetoelastic coupling between the lattice and the two nearly anti-parallel spins. The revised spin model for BiFeO$_3$ contains two new single-ion anisotropy terms that violate rhombohedral symmetry and depend on the direction of the magnetic field.
Magnetoelectric effect in multiferroic metals via a direct spin-charge interaction
Key Lab of advanced optoelectronic quantum architecture and measurement (MOE), and School of Interdisciplinary Science, Beijing Institute of Technology（北京理工大学光电量子架构与测量教育部重点实验室，交叉科学研究院）
Single-phase multiferroic materials are usually considered useless because of the weak magnetoelectric effects, low operating temperature, and small electric polarization induced by magnetic orders. As a result, current studies on applications of the magnetoelectric effects are mainly focusing on multiferroic heterostructures and composites. Here we report a room-temperature giant effect in response to external magnetic fields in single-phase multiferroics. A low magnetic field of 1000 Oe applied on the spin-driven multiferroic hexaferrites BaSrCo2Fe11AlO22 and Ba0.9Sr1.1Co2Fe11AlO22 is able t…
In this contribution to the special issue on magnetoelectrics and their applications, we focus on some single phase multiferroics theoretically predicted and/or experimentally discovered by the authors in recent years. In these materials, iron is the common core element. However, these materials are conceptually different from the mostly-studied BiFeO$_3$, since their ferroelectricity is improper. Our reviewed materials are not simply repeating one magnetoelectric mechanism, but cover multiple branches of improper ferroelectricity, including the magnetism-driven ferroelectrics, geometric ferro…
Magnetoelectrical control of nonreciprocal microwave response in a multiferroic helimagnet
对外场物理性质的控制是当代技术的基本要求。可以通过场效应晶体管中的栅极电场来控制电导，场效应晶体管是集成电路的主要部件。由电场引起的光学现象如电致发光和电致变色对于显示器和其它技术是有用的。微波传播的控制对于未来的无线通信技术也是必不可少的。固体中的微波性质主要由磁激发控制，而磁激发不容易由电场控制。这个问题的解决方案之一是利用磁感应铁电体（多铁性）。在这里，我们表明，微波非互易性，这是相反传播的微波之间的差异，可以逆转的外电场在多铁性helimagnet Ba $_2$ Mg $_2$ Fe $_{12}$ O $_{22}$。这一结果为微波特性的电控制提供了新的途径。
Magnetoelectric composites are an important class of multiferroic materials that pave the way towards a new generation of multifunctional devices directly integrable in data storage technology and spintronics. This study focuses on strain-mediated electrical manipulation of magnetization in an extrinsic multiferroic. The composite includes 5 nm or 60 nm Fe$_{81}$Ga$_{19}$ thin films coupled to a piezoelectric (011)-PMN-PZT. The magnetization reversal study reveals a converse magnetoelectric coefficient $α_\mathrm{CME,max} \approx 2.7 \times {10^{-6}}$ s.m$^{-1}$ at room temperature. This repor…
Materials with a coexistence of magnetic and ferroelectric order (i.e., multiferroics) provide an efficient route for the control of magnetism by electric fields. Unfortunately, a long-sought room temperature multiferroic with strongly coupled ferroelectric and ferromagnetic (or ferrimagnetic) orderings is still lacking. Here, we propose that hydrogen intercalation in antiferromagnetic transition metal oxides is a promising way to realize multiferroics with strong magnetoelectric coupling. Taking brownmillerite SrCoO2.5 as an example, we show that hydrogen intercalated SrCoO2.5 displays strong…
We report the effect of Ba and Zr co-substitution on structural, dielectric, magnetic and magnetoelectric properties of BiFeO3 multiferroics. Polycrystalline nanoceramic samples of Bi1- xBaxFe1-yZryO3 have been synthesized by auto-combustion method. Rietveld refinement result of X-ray diffraction data indicate a contraction of unit cell volume with increase in x and y. Field emission scanning electron micrographs show densely populated grains without any voids or defects with well-defined grain boundary and decrease in grain size with increasing x and y. The result of dielectric measurement di…
Antiferromagnets (AFMs) are presently considered as promising materials for applications in spintronics and random access memories due to the robustness of information stored in AFM state against perturbing magnetic fields (P. Wadley et al., Science 351, 587 (2016)). In this respect, AFM multiferroics maybe attractive alternatives for conventional AFMs as the coupling of magnetism with ferroelectricity (magnetoelectric effect) offers an elegant possibility of electric field control and switching of AFM domains. Here we report the results of comprehensive experimental and theoretical investigat…
In this work, we have designed obtained a novel multiferroic nanocomposite using the high-pressure torsion (HPT) method. The crystal structure, phase composition, morphology, ferromagnetic (FM) and ferroelectric (FE) properties of the initial powders and "multiferroic-ferromagnetic" nanocomposites have been studied comprehensively. The initial powders and their composites show the perovskite and spinel crystalline phases for the FE and FM fractions, respectively. After HPT, the particle sizes of the initial powders are decreased significantly. It is shown that the novel nanocomposite consists …
Simultaneously Magnetic- and Electric-dipole Active Spin Excitations Govern the Static Magnetoelectric Effect in Multiferroic Materials
我们推导出一个求和规则，证明静态磁电（ME）效应是由光学跃迁，同时激发通过光的电和磁分量。通过对磁点群的系统分析，我们证明了ME求和规则适用于包括ME多铁性化合物在内的各种非中心对称磁体。由于动态ME效应，这些材料中的光学激发可以表现出方向二向色性，即对于反向传播的光束，吸收系数可以不同。根据ME求和规则，材料的线性ME效应的大小主要由其低能光激发的方向二色性决定。应用求和规则的多铁性Ba $_2$ CoGe $_2$ O $_7$，Sr $_2$ CoSi $_2$ O $_7$和Ca $_2$ CoSi $_2$ O $_7$表明，在这些化合物中，静态ME效应主要由GHz-THz光谱范围内的自旋波激发的方向二向色性决定。在此基础上，我们认为，方向二向色性的研究和ME求和规则的应用可以促进具有大静态ME效应的新材料的合成。
