论文标题
“兄弟双胞胎”铁电性：第一原理中氢气的samarium镍的极性状态
"Fraternal-twin" ferroelectricity: competing polar states in hydrogen-doped samarium nickelate from first principles
论文作者
论文摘要
氢的可逆插入到镍盐，Smnio $ _3 $（SNO）的近期引起了人们的兴趣。进入SNO后，氢离解会分解：H $^+$与氧气结合，并在附近的NiO $ _6 $ _6 $ octahedron上定位于氧气，从而产生了局部偶极矩。在这项工作中，我们使用第一原理计算以每Ni的浓度为1/4氢探索掺杂氢的SNO的极性。 SNO的固有倾斜模式和间质氢的存在提出了无法克服的能量屏障，可以将这些极性状态切换为反转下与对称性相关的状态。我们发现一个足够低的屏障将局部电子移至相邻的NIO $ _6 $ octahedron，这是一个与对称性无关的状态，但在外延菌株下的能量相等，导致极化发生了巨大变化。我们称这种非常规的铁电A“兄弟双胞胎”铁电。
Reversible intercalation of hydrogen into samarium nickelate, SmNiO$_3$ (SNO), has been of recent interest. Upon entering SNO, the hydrogen dissociates: the H$^+$ binds to an oxygen and the valence electron localizes on a nearby NiO$_6$ octahedron, resulting in a local dipole moment. In this work, we use first-principles calculations to explore the polar states of hydrogen-doped SNO at a concentration of 1/4 hydrogen per Ni. The inherent tilt pattern of SNO and the presence of the interstitial hydrogen present an insurmountable energy barrier to switch these polar states to their symmetry-related states under inversion. We find a sufficiently low barrier to move the localized electron to a neighboring NiO$_6$ octahedron, a state unrelated by symmetry but equal in energy under epitaxial strain, resulting in a large change in polarization. We term this unconventional ferroelectric a "fraternal-twin" ferroelectric.
