We present a first-principles scheme for computing the magnetoelectric response of multiferroics. We apply our method to BiFeO3 (BFO) and related compounds in which Fe is substituted by other magnetic species. We show that under certain relevant conditions -- i.e., in absence of incommensurate spin modulation, as in BFO thin films and some BFO-based solid solutions -- these materials display a large linear magnetoelectric response. Our calculations reveal the atomistic origin of the coupling and allow us to identify the most promising strategies to enhance it.
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）
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）
Prediction of new multiferroic and magnetoelectric material Fe3Se4
目前，具有磁电耦合的多铁性材料在新型存储器件领域有着广泛的应用。在室温下制备具有强耦合铁电和亚铁磁有序结构的多铁性材料具有挑战性。硒化铁（Fe_3Se_4）单晶在室温下表现出铁电有序和磁有序共存的II型多铁性。我们研究了铁电金属Fe_3Se_4的晶格不稳定性、电子结构、铁电、亚铁磁有序和输运性质。态密度显示出在费米能级附近Fe-3d和Se-4p态的相当大的杂化，证实了其金属行为。Fe阳离子的磁矩遵循II型亚铁磁和铁电有序，计算出的总磁矩为4.25每晶胞（Fe 6 Se 8）。Fe-Se的强共价键性质导致其铁电性质。此外，对称性分析表明，3d-t2 g轨道有序的Fe亚晶格的倾斜是由于Jahn-Teller（JT）畸变引起的。这项研究为利用多铁性材料发展自旋电子学相关技术提供了进一步的见解。
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）
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…
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。
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。
Symmetry Analysis of Magnetoelectric Coupling Effect in All Point Groups
National Laboratory of Solid State Microstructures and School of Physics, Nanjing University（南京大学固体微结构物理国家重点实验室和物理学院）；Collaborative Innovation Center of Advanced Microstructures, Nanjing University（南京大学先进微结构协同创新中心）；Key Laboratory of Computational Physical Sciences (Ministry of Education), Institute of Computational Physical Sciences, and Department of Physics, Fudan University（复旦大学计算物理教育部重点实验室、计算物理科学研究所和物理系）
