Using single-crystal X-ray diffraction we characterise the 235\,K incommensurate phase transition in the hybrid molecular framework tetraethylammonium silver(I) dicyanoargentate, [NEt$_4$]Ag$_3$(CN)$_4$. We demonstrate the transition to involve spontaneous resolution of chiral [NEt$_4$]$^+$ conformations, giving rise to a state in which molecular chirality is incommensurately modulated throughout the crystal lattice. We refer to this state as an incommensurate chirality density wave (XDW) phase, which represents a fundamentally new type of chiral symmetry breaking in the solid state. Drawing on parallels to the incommensurate ferroelectric transition of NaNO$_2$ we suggest the XDW state arises through coupling between acoustic (shear) and molecular rotoinversion modes. Such coupling is symmetry-forbidden at the Brillouin zone centre but symmetry-allowed for small but finite modulation vectors $\mathbf q=[0,0,q_z]^\ast$. The importance of long-wavelength chirality modulations in the physics of this hybrid framework may have implications for the generation of mesoscale chiral textures, as required for advanced photonic materials.
Role of magnetic chirality in polarization flip upon commensurate-incommensurate magnetic phase transition in YMn$_{2}$O$_{5}$
我们用极化中子和沿b轴方向的电极化同时测量了YMn $^{4+}$(Mn $_{1-x}$ Ga $_{x}$)$^{3+}$ O $_{5}$($x=0.047$和0.12)单晶的磁手征,其中Ga离子稀释Mn $^{3+}$的自旋。$x=0.047$样品表现出高温无公度(HT-ICM)、公度(CM)和低温无公度(LT-ICM)磁相,其顺序为温度降低,而$x=0.12$样品仅表现出HT-ICM和LT-ICM相。在这里,CM和LT-ICM相分别是铁电的和弱铁电的。在各种场冷却条件下进行的零场加热下的测量表明,CM和LT-ICM相的自旋驱动铁电性的微观机制是不同的:Mn $^{4+}$摆线自旋的磁手性在LT-ICM相中起主导作用,而Mn $^{4+}$ -Mn $^{3+}$链的磁交换伸缩在CM相中起主导作用。YMn $_{2}$ O $_{5}$的极化在CM到LT-ICM的相变中翻转,这是因为由磁手性和交换伸缩驱动的铁电性提供了相反的极化方向。
Hybrid improper dipolar density wave in NaLaCoWO$_6$
由于两种非极性八面体畸变的组合,混合不适当铁电性(HIF)允许在AA'BB' O $_6$双钙钛矿材料中产生电极化。然而,对于A/A'阳离子的选定组合,观察到具有平均对称性$C2/m$的非极性无公度相。由于详细的晶体学描述的无公度相,电子,中子和X射线衍射数据的基础上,我们表明,无公度调制有关的突变的相位倾斜沿a-和c-轴,而沿b-轴的倾斜保持恒定的整个结构。通过群论和对称性分析,我们发现,我们观察到一个无公度类似的HIF诱导的混合不正常偶极密度波在NaLaCoWO $_6$。偶极排序也是由于在这种情况下,涉及相称和不相称的八面体倾斜的三线性不变。
Chirality-induced magnetoresistance in hybrid organic-inorganic perovskite semiconductors
National Laboratory of the Rockies(落基山国家实验室);Renewable and Sustainable Energy Institute, University of Colorado Boulder(科罗拉多大学博尔德分校可再生能源与可持续能源研究所);North Carolina State University(北卡罗来纳州立大学);University of Wisconsin-Madison(威斯康星大学麦迪逊分校);Center for Hybrid Organic Inorganic Semiconductors for Energy(能源混合有机无机半导体中心)
Enantiopurity-Controlled Magnetism in a Two-Dimensional Organic-Inorganic Material
University of California, Berkeley(加州大学伯克利分校);Lawrence Berkeley National Laboratory(劳伦斯伯克利国家实验室);Molecular Foundry, Lawrence Berkeley National Laboratory(劳伦斯伯克利国家实验室分子发现中心);Kavli Energy NanoScience Institute(卡弗里能源纳米科学研究所);Chemical Sciences Division, Lawrence Berkeley National Laboratory(劳伦斯伯克利国家实验室化学科学部)
Direct Quantification of Molecular Helicity-Dependent Effective Magnetic Fields in Chiral Polypeptide/Ferromagnet Heterostructures
Johannes Gutenberg-Universität Mainz(美因茨约翰内斯古腾堡大学);Helmholtz Institute Mainz(美因茨亥姆霍兹研究所);The Hebrew University of Jerusalem(耶路撒冷希伯来大学);GSI Helmholtz-Zentrum für Schwerionenforschung GmbH(德国重离子研究中心亥姆霍兹有限公司);University of California, Berkeley(加州大学伯克利分校);Uppsala University(乌普萨拉大学);Norwegian University of Science and Technology(挪威科技大学)
Chiral properties of the zero-field spiral state and field-induced magnetic phases of the itinerant kagome metal YMn$_6$Sn$_6$
在YMn $_6$ Sn $_6$的六边形平面中施加磁场导致公度相和非公度相的复杂磁相图,其中之一与由独特的波动驱动机制产生的拓扑霍尔效应(THE)共存。使用非极化中子衍射,我们报告解决了两个先前确定的,但未知的,相称的阶段的磁结构。这些包括低温,高场扇形相和室温,低场倾斜反铁磁相。扇形和强制铁磁相之间的中间无公度相也被确定为最后一个已知的平面内场-温度图相。使用同步加速器粉末衍射的额外表征揭示了极高质量的单相晶体,这表明在整个相图的大部分区域中存在两个不相称的磁性结构是该系统的固有特性。有趣的是,极化中子衍射表明,中心对称系统主机优先手性在零场双平面螺旋相,这与THE,是一个拓扑非平凡的特点。
Observation of a non-reciprocal skyrmion Hall effect of hybrid chiral skyrmion tubes in synthetic antiferromagnetic multilayers
Tohoku University(东北大学);Johannes Gutenberg-Universität Mainz(约翰内斯·古腾堡美因茨大学);Singulus Technologies AG(辛古卢斯科技有限公司);Forschungszentrum Jülich(于利希研究中心);Max Planck Institute for Intelligent Systems(马克斯·普朗克智能系统研究所);Helmholtz-Zentrum Berlin für Materialien und Energie GmbH(亥姆霍兹柏林材料与能源中心);Paul Scherrer Institut(保罗谢尔研究所);Norwegian University of Science and Technology(挪威科技大学)
First-principles calculations of spin-split bands in chiral hybrid organic-inorganic perovskites ($R$/$S$-PEA)PbI$_3$ and ($R$/$S$-NEA)PbI$_3$
Institute for Materials Research, Tohoku University(东北大学物质材料研究所学);Department of Applied Physics, Tokyo University of Science(东京科学大学应用物理系);School of Advanced Science and Engineering, Waseda University(早稻田大学先进理工学研究院)
Competing incommensurability, electronic correlations, and superconductivity in a hybrid transition metal dichalcogenide
Weizmann Institute of Science(魏茨曼科学研究所);University of Hamburg(汉堡大学);Bar Ilan University(巴伊兰大学);The Pennsylvania State University(宾夕法尼亚州立大学);Technion - Israel Institute of Technology(以色列理工学院);Goethe Universität Frankfurt(法兰克福歌德大学)
Chiral molecule-induced contributions to ferromagnetic resonance
Helmholtz-Zentrum Dresden–Rossendorf(德累斯顿-罗森多夫亥姆霍兹中心);Universidad Técnica Federico Santa María(费德里科·圣玛丽亚技术大学);Universität Duisburg–Essen(杜伊斯堡-埃森大学);Chemnitz University of Technology(开姆尼茨工业大学);Adam Mickiewicz University(亚当·密茨凯维奇大学)
Chiral Porphyrin Monolayers on Ferromagnetic Thin Films: Ultrafast Spectroscopy of Hybrid Interfaces
Faculty of Chemistry, Adam Mickiewicz University(亚当·密茨凯维奇大学化学系);Center for Advanced Technologies, Adam Mickiewicz University(亚当·密茨凯维奇大学先进技术中心);Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research(德累斯顿-罗斯多夫亥姆霍兹中心离子束物理与材料研究所);Faculty of Physics and Astronomy, Adam Mickiewicz University(亚当·密茨凯维奇大学物理与天文学系)