Multiferroizität in niedrigdimensionalen magnetischen Systemen mit unterschiedlichen Spins

具有不同自旋的低维磁系统的多铁性

• 批准号: 388987880
• 负责人: Professor Dr. Rüdiger Klingeler
• 金额: --
• 依托单位: Faculty of Physics
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/388987880?language=en
• 关键词: Multiferroizit; niedrigdimensionalen; magnetischen; Systemen; mit

This German-Russian project aims at investigating magnetoelectric and multiferroic phenomena in the class of low-dimensional mixed spin systems of the howardevansite structure type. This rich and practically uninvestigated family of metal oxides includes, in particular, Fe7(PO4)6, NaFe7(PO4)6, LiCuFe2(VO4)3, and NaCuFe2(VO4)3 which will be studied in beginning of the project while new materials will be addressed furtheron. Our preliminary investigations indicate the presence of significant magnetodielectric coupling in the magnetically ordered state of some of these compounds. At present, magnetically low-dimensional materials such as the howardevansite-type ones at hand with sequences (chains) of different spins are rather rarely studied. The appearance of spontaneous electric polarization in these systems is associated with the formation of non-collinear long-period magnetic structures. In the frame of this project, the synthesis by means of hydrothermal and solid-state methods as well as a variety of sophisticated experimental studies will be applied. To be specific, in addition to standard characterization techniques we will study the specific heat, thermal expansion and magnetostriction, magnetization, pulsed field magnetization, dielectric permittivity, and the dielectric polarization. Application of magnetic field up to 18 T (static) and 35 T (pulsed) will enable constructing the magnetic phase diagrams. In addition, the magnetic ground state will be studied by means of high-frequency Electron-Spin Resonance-Spectroscopy and Muon-Spin-Rotation. This rich variety of methods will provide all relevant information on the magneto-elastic-dielectric couplings, thereby enabling in collaboration with our theory partners to elucidate the mechanisms of magnetelectric coupling and multiferroicity in this class of compounds. As a side activity, the electrochemical properties of Li-based materials will be studied and in-situ SQUID magnetometry will be performed in order to investigate the effect of delithiation on the magnetic properties. We believe that the project will not only yield several particular examples of materials with strong magneto-dielectric coupling realized by a new mechanism in materials with unusual sequences of different spins but will also open an avenue towards a new family of multiferroics and magnetoelectrics.

这个德国和俄罗斯合作的项目旨在研究低维混合自旋系统中的磁电和多铁性现象。这一丰富且几乎未被研究的金属氧化物家族包括，特别是Fe7(PO4)6, NaFe7(PO4)6, LiCuFe2(VO4)3和NaCuFe2(VO4)3，这些将在项目开始时进行研究，而新材料将进一步研究。我们的初步研究表明，在这些化合物的磁有序态中存在显著的磁介电耦合。目前，对具有不同自旋序列（链）的磁性低维材料（如霍华德德斑岩型材料）的研究相当少。在这些体系中自发电极化的出现与非共线长周期磁结构的形成有关。在本项目框架内，将采用水热法和固相法合成以及各种复杂的实验研究。具体来说，除了标准的表征技术，我们将研究比热，热膨胀和磁致伸缩，磁化，脉冲场磁化，介电常数和介电极化。应用高达18t（静态）和35t（脉冲）的磁场将能够构建磁相图。此外，将利用高频电子自旋共振光谱和介子自旋旋转来研究磁基态。这种丰富多样的方法将提供磁-弹性-介电耦合的所有相关信息，从而使我们的理论合作伙伴能够阐明这类化合物的磁电耦合和多铁性机制。作为副活性，我们将研究锂基材料的电化学性能，并进行原位SQUID磁强计来研究脱硫对其磁性能的影响。我们相信，该项目不仅将产生几个特殊的材料实例，通过具有不同自旋序列的材料的新机制实现强磁介电耦合，而且还将为多铁性和磁电性的新家族开辟一条道路。