Multiferroicity in skyrmionic materials

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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.