Park S-H, Liu B-Q, Behal D, Pedersen B, Schneidewind A
Department for Earth and Environmental Sciences, Section Crystallography, Ludwig-Maximilians-Universität München, Theresienstrasse 41, 80333 Munich, Germany.
J Phys Condens Matter. 2018 Apr 4;30(13):135802. doi: 10.1088/1361-648X/aaaeae. Epub 2018 Mar 2.
The low temperature antiferromagnetic (AF) phase of MnWO (the so-called AF1 phase) exhibits different spin-canting configurations at two Mn sublattices of the (3 + 1)-dimensional magnetic structure. The suggested superspace group [Formula: see text] is a significant consequence of the polar space group [Formula: see text]2 true for the nuclear structure of MnWO. Density functional theory calculations showed that its ground state prefers this two spin-canting system. The structural difference between two independent atomic sites for Mn (Mn , Mn ) is too small to allow microscopically detectable electric polarisation. However, this hidden intrinsic polar character allows AF1 two commensurately modulated spin-canting textures. This is considered as the prerequisite onset of the improper ferroelectricity enhanced by the helical spin order in the multiferroic phase AF2 of MnWO.
MnWO₄的低温反铁磁（AF）相（即所谓的AF1相）在（3 + 1）维磁性结构的两个Mn亚晶格上表现出不同的自旋倾斜构型。所提出的超空间群[公式：见正文]是极性空间群[公式：见正文]2的一个重要结果，这对于MnWO₄的核结构是成立的。密度泛函理论计算表明，其基态更倾向于这种双自旋倾斜系统。Mn的两个独立原子位点（Mn¹，Mn²）之间的结构差异太小，以至于无法通过微观手段检测到电极化。然而，这种隐藏的内在极性特征允许AF1出现两种相称调制的自旋倾斜纹理。这被认为是在MnWO₄的多铁性相AF2中由螺旋自旋序增强的非本征铁电性的先决条件。
