标题： 金属自由杂化分子晶体中的非共线铁电相和螺旋型反铁电相 显示英文标题

标题： Noncollinear ferroelectric and screw-type antiferroelectric phases in a metal-free hybrid molecular crystal

摘要： 非共线偶极纹理大大扩展了铁电材料的科学价值和应用前景。 事实上，非共线自旋纹理已被广泛认为是凝聚态物理的核心问题之一，例如具有多铁性的螺旋/锥形磁体和具有拓扑性质的磁斯格明子。 然而，电极化材料中的对应物研究较少，因此亟需探索，因为电偶极子在大多数铁电/反铁电材料中通常呈共线排列。 具有电偶极子的分子晶体为探索非共线极性提供了丰富的素材。 在这里，我们报告了一种有机盐（H2Dabco）BrClO4（H2Dabco = N,N'-1,4-二氮杂双环[2.2.2]辛烷𬭩），它表现出铁电相和反铁电相之间的转变。 基于实验表征和从头计算，发现其电偶极子呈现出非平凡的非共线纹理，相邻偶极子之间具有$60^\circ$-扭转角度。 然后，铁电-反铁电转变可以理解为扭转角度序列的编码。 我们的研究揭示了非共线电极性的独特科学。 显示英文摘要

摘要： Noncollinear dipole textures greatly extend the scientific merits and application perspective of ferroic materials. In fact, noncollinear spin textures have been well recognized as one of the core issues of condensed matter, e.g. cycloidal/conical magnets with multiferroicity and magnetic skyrmions with topological properties. However, the counterparts in electrical polarized materials are less studied and thus urgently needed, since electric dipoles are usually aligned collinearly in most ferroelectrics/antiferroelectrics. Molecular crystals with electric dipoles provide a rich ore to explore the noncollinear polarity. Here we report an organic salt (H2Dabco)BrClO4 (H2Dabco = N,N'-1,4-diazabicyclo[2.2.2]octonium) that shows a transition between the ferroelectric and antiferroelectric phases. Based on experimental characterizations and ab initio calculations, it is found that its electric dipoles present nontrivial noncollinear textures with $60^\circ$-twisting angle between the neighbours. Then the ferroelectric-antiferroelectric transition can be understood as the coding of twisting angle sequence. Our study reveals the unique science of noncollinear electric polarity.