Multiferroicity in skyrmionic materials

最近在腔隙尖晶石GaV4S8 （GVS）中发现的铁电性和非常规天粒子自旋织体共存，预示着这些化合物中会发生出色的磁电效应。值得注意的是，GVS是迄今为止已知的第一个也是唯一一个有可能进入顶级现代应用领域的多铁性材料，比如skyronic存储器。为了进一步深入了解GVS及其相关化合物的基本静态和动态行为，我们建议在这个双边项目中，通过理论和实验之间的协调纳米尺度方法来阐明GVS及其相关化合物的基本静态和动态行为。更准确地说，我们独特地将局部尺度实验检测（通过使用各种扫描探针技术和光谱学）与多尺度建模策略（即ab-initio，相场建模等）结合起来。捷克共和国布拉格（理论）和德国德累斯顿（实验）的两个参与小组构成了在拟议的双边项目中进行这项研究的理想基础。因此，项目的目标有三个方面：首先，GVS和其他家族成员（如GeV4S8、GaMo4S8、GaV4Se8）的磁电耦合机制需要一个全面和基本的理解，只有通过我们共同的理论和实验的努力和互补才能获得。其次，所有这些化合物都将受到外部刺激，如机械应变、电场、磁场和光场，以有目的地影响这些独特材料中天元相的相图；例如，我们期望磁性结构，即摆线晶格/天粒子晶格向能量有利的方向旋转。第三，这些刺激也将允许研究这些材料在局部1纳米长度尺度上的动力学特性。

The recently discovered coexistence of both ferroelectricity and non-conventional skyrmionic spin textures in the lacunar spinel GaV4S8 (GVS) promises outstanding magneto-electric effects to happen in these compounds. Notably, GVS is the first and only multiferroic material known to date that potentially might find its way into top-modern applications such as skyrmionic memories. In order to significantly advance the fundamental understanding, we propose in this bilateral project to shed light onto the fundamental static and dynamic behavior of GVS and its related compounds, through the concerted nanoscale approach between theory and experiment. More precisely, we uniquely combine the local-scale experimental inspection (by using various scanning probe techniques and optical spectroscopy) with multi-scale modeling strategies (i.e. ab-initio, phase field modeling, etc.). The two participating teams in Prague/Czech Republic (theory) and Dresden/Germany (experiment) form the ideal basis in order to conduct this research in the proposed bilateral project.The project goals thus are threefold: Firstly, the mechanism of magneto-electric coupling in the GVS and other family members such as GeV4S8, GaMo4S8, GaV4Se8 need a comprehensive and fundamental understanding that can be obtained through our concerted and complementary theoretical and experimental efforts, only. Secondly, all these compounds will be subjected to external stimuli such as mechanical strain, electric, magnetic and optical fields in order to purposely impact the phase diagram of the skyrmionic phases in these unique materials; for instance, we expect the magnetic textures, i.e. the cycloidal / skyrmionic lattice to rotate into energetically favorable directions. Thirdly, these stimuli will allow also to study the dynamical properties of these materials on the local 1-nm length scale.