论文标题
合作集群jahn-teller效应是抗fiferroelectricity的可能途径
Cooperative cluster-Jahn-Teller effect as a possible route to antiferroelectricity
论文作者
论文摘要
我们报告了观察到由非常规的显微镜机制驱动的立方ganb $ _4 $ s $ _8 $的观察，这是NB $ _4 $ S $ _4 $分子群的合作Jahn-Teller效应。抗极性性质的分配是基于晶体结构的突然变化和在$ t_ \ mathrm {jt} = 31 $ \，k处的介电常数的强滴，也表明了过渡的一阶性质。此外，我们发现局部对称性降低先于远程轨道顺序，这意味着在$ t_ \ mathrm {jt} $的高于$ t_ \ mathrm {jt} $的立方相中存在动态jahn-teller效应。根据Lacunar尖晶石报道的各种结构多晶型物的种类，还包括铁电相，我们认为GANB $ _4 $ s $ _8 $可能可以转化为铁电状态，这将进一步将观察到的抗波拉相分类为抗抗固体。
We report the observation of an antipolar phase in cubic GaNb$_4$S$_8$ driven by an unconventional microscopic mechanism, the cooperative Jahn-Teller effect of Nb$_4$S$_4$ molecular clusters. The assignment of the antipolar nature is based on sudden changes in the crystal structure and a strong drop of the dielectric constant at $T_\mathrm{JT}=31$\,K, also indicating the first-order nature of the transition. In addition, we found that local symmetry lowering precedes long-range orbital ordering, implying the presence of a dynamic Jahn-Teller effect in the cubic phase above $T_\mathrm{JT}$. Based on the variety of structural polymorphs reported in lacunar spinels, also including ferroelectric phases, we argue that GaNb$_4$S$_8$ may be transformable to a ferroelectric state, which would further classify the observed antipolar phase as antiferrolectric.
