In our previous study, we demonstrated the existence of an unidentified ferroelectric smectic phase in the low-temperature region of the ferroelectric smectic A phase, where the layer spacing decreases with decreasing temperature. In the present study, we identified the phase by taking 2D X-ray diffraction images of a magnetically oriented sample while allowing it to rotate and constructed a 3D reciprocal space with the sample rotation angle as the third axis for the whole picture of the reciprocal lattice vectors originating from the smectic structure. Consequently, circular diffraction images were obtained when the reciprocal lattice vectors were evenly distributed on the conical surface at a certain inclination angle in the reciprocal space. This result provides clear evidence that the phase in question was smectic C. The polarization properties also showed that the observed smectic C phase had spontaneous polarization in the direction parallel to the director and was identified as ferroelectric smectic C. These results provide a new type of classification for liquid crystalline phases that has been established over many years and is a significant contribution to the basic science of soft matter research.
Effective elastic theory of smectic-A and smectic-C liquid crystals
本文从广义Chen-Lubensky模型出发，通过绝热消去取向自由度，解析地导出了近晶-A和近晶-C液晶的有效层弹性能。在近晶-A相，计算作为层波动模式的波长的函数的有效层弯曲弹性模量。事实证明，对于小于指向矢穿透长度的波长，层法线和指向矢的解锁降低了层的弯曲刚度。在非手性近晶-C相中，由于层间位移和指向矢之间的耦合，出现了各向异性的弯曲弹性。有效层抗弯刚度计算为层波动波矢和指向矢场之间的角度$\vartheta$的函数。我们计算自由能极小值$\vartheta=θ$。结果表明，$θ$随倾角、波动波长和其他弹性常数的不同而从$0°$变化到$90°$。我们还发现了一个新的重要特征长度和$θ$的不连续变化。利用Chen-Lubensky模型的弹性常数，我们确定了更宏观的模型[Y. Hatwalne和T. C. Lubensky，Phys. Rev. E { \bf 52}，6240（1995）]。然后，我们讨论了流体力学，并证明了定向器的排列和各向异性层位移波的传播中存在的振荡壁和振动圆柱源分别。
On the emergence of molecular tilt in a ferroelectric smectic liquid crystal with broken director-inversion symmetry
University of the Basque Country EHU（巴斯克大学）；Universidad de Zaragoza（萨拉戈萨大学）；Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza（阿拉贡纳米科学与材料研究所（INMA），西班牙国家研究委员会-萨拉戈萨大学）；Universitat Politècnica de Catalunya（加泰罗尼亚理工大学）
We have structurally characterized the liquid crystal phase that appears as an intermediate state when a dielectric nematic, having polar disorder of its molecular dipoles, transitions to the almost perfectly polar-ordered ferroelectric nematic. This intermediate phase, which fills a 100-year-old void in the taxonomy of smectics and which we term the "smectic $Z_A$", is antiferroelectric, with the nematic director and polarization oriented parallel to smectic layer planes, and the polarization alternating in sign from layer to layer. The period of this polarization wave ($\sim$180 A) is mesosc…
We report the smectic $A_F$, a new liquid crystal phase of the ferroelectric nematic realm. The smectic $A_F$ is a phase of small polar, rod-shaped molecules which form two-dimensional fluid layers spaced by approximately the mean molecular length. The phase is uniaxial, with the molecular director, the local average long-axis orientation, normal to the layer planes, and ferroelectric, with a spontaneous electric polarization parallel to the director. Polarization measurements indicate almost complete polar ordering of the $\sim 10$ Debye longitudinal molecular dipoles, and hysteretic polariza…
Modulated Anti-Ferroelectric Smectic Phases with Orthogonal and Tilted Structures
School of Physics & Astronomy, University of Leeds（利兹大学物理与天文学院）；School of Chemistry, University of Leeds（利兹大学化学学院）；Complex Matter Department, Jožef Stefan Institute（约瑟夫·斯蒂芬研究所复杂物质部）；Faculty of Mathematics and Physics, University of Ljubljana（卢布尔雅那大学数学与物理学院）
Curvature-induced smectic-C order of tangentially anchored hard spherocylinders on a sphere with a rigidly locked director field
Recognition Physics Institute（Recognition物理研究所）；Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf（杜塞尔多夫海因里希·海涅大学软物质理论物理第二研究所）；Department of Physics, Case Western Reserve University（凯斯西储大学物理系）；Theoretical Department, Joint Institute for High Temperatures, RAS（俄罗斯科学院高温联合研究所理论部）
We investigate the anomalous dynamics in smectic phases of short host rods where, counter-intuitively, long guest rod-shaped particles diffusive faster than the short host ones, due to their precise size mismatch. In addition to the previously reported mean-square displacement, we analyze the time evolution of the Self-van Hove functions G(r,t), as this probability density function uncovers intrinsic heterogeneous dynamics. Through this analysis, we show that the dynamics of the host particles parallel to the director becomes non-gaussian and therefore heterogeneous after the nematic-to-smecti…
Short pitch structures in smectics with interactions over more than two layers
介绍了手性极性近晶相互作用的唯象模型。自由能的最小化给出了三种稳定的结构：铁电SmC $^*$相、反铁电SmC $^*_A$相和SmC $^*_H$相的螺旋调制结构。Sm C $^*_α$相可被认为是Sm C $^*_H$相，低于Sm A相，当出现在Sm C $^*$相和Sm C $^*_A$相之间时，可被认为是Sm C $^*_{FI2}$相或Sm C $^*_{FI1}$相。分析了这些相的稳定性，给出了模型参数空间的相图。
A ferroelectric liquid crystal confined in cylindrical nanopores: Reversible smectic layer buckling, enhanced light rotation and extremely fast electro-optically active Goldstone excitations
Selective reflection of light in glassforming ternary liquid crystalline mixtures
Institute of Nuclear Physics, Polish Academy of Sciences（波兰科学院核物理研究所）；AGH University of Cracow（克拉科夫AGH科技大学）；Faculty of Materials Science and Ceramics, AGH University of Cracow（克拉科夫AGH科技大学材料科学与陶瓷学院）；Jagiellonian University（雅盖隆大学）；Faculty of Chemistry, Jagiellonian University（雅盖隆大学化学系）；Military University of Technology（军事理工大学）；Institute of Chemistry, Military University of Technology（军事理工大学化学研究所）；Osaka University（大阪大学）；Graduate School of Science, Osaka University（大阪大学理学研究科）；Research Center for Thermal and Entropic Science, Graduate School of Science, Osaka University（大阪大学理学研究科热与熵科学研究中心）
Recent discovery of the ferroelectric nematic phase N_F resurrects a question about stability of the uniform N_F state with respect to the formation of either standard for solid ferroelectrics domain structure, or often occurring in liquid crystals space modulation of the polarization vector P (and naturally coupled to P nematic director. In this work within Landau mean-field theory we investigate the linear stability of the minimal model admitting the conventional paraelectric nematic N and N_F phases. Our minimal model, (besides the standard terms of the expansion over P and director gradien…
