标题： 韦尔铁电半金属 显示英文标题

标题： Weyl Ferroelectric Semimetal

摘要： 最近发现的铁电金属和外尔半金属（WSM）引发了一个自然的问题：这两种奇异的物质状态是否可以在一种材料中共存。 这些发现使我们确信从物理上来说这是可能的，因为它们都共享相同的必要条件，即破坏了反演对称性。 在这里，通过第一性原理计算，我们证明实验合成的非磁性 HgPbO$_3$是这种混合“\emph{韦尔铁电半金属}”的独特例子。 其中心对称的$R\bar{3}c$相将经历铁电相变，转变为铁电的$R3c$结构。 这两个相都是金属的，铁电相具有 33$\mu$C/cm$^2$的自发极化。 最重要的是，它在费米能级附近还拥有六对手性外尔节点，使其成为氧化物外尔半金属。 结构对称性破缺的相变诱导了拓扑相变。 HgPbO$_3$中铁电性和外尔节点的共存为探索多相相互作用和相互控制提供了一个理想的平台。 外加脉冲电场可以调节外尔节点，这在集成拓扑电子器件和铁电器件的潜在应用方面前景广阔。 显示英文摘要

摘要： The recent discoveries of ferroelectric metal and Weyl semimetal (WSM) have stimulated a natural question: whether these two exotic states of matter can coexist in a single material or not. These two discoveries ensure us that physically it is possible since both of them share the same necessary condition, the broken inversion symmetry. Here, by using first-principles calculations, we demonstrate that the experimentally synthesized nonmagnetic HgPbO$_3$ represents a unique example of such hybrid "\emph{Weyl ferroelectric semimetal}". Its centrosymmetric $R\bar{3}c$ phase will undergo a ferroelectric phase transition to the ferroelectric $R3c$ structure. Both phases are metallic and the ferroelectric phase owns a spontaneous polarization of 33 $\mu$C/cm$^2$. Most importantly, it also harbors six pairs of chiral Weyl nodes around the Fermi level to be an oxide WSM. The structural symmetry broken phase transition induces a topological phase transition. The coexistence of ferroelectricity and Weyl nodes in HgPbO$_3$ is an ideal platform for exploring multiphase interaction and mutual control. The Weyl nodes can be tuned by external pulse electric field, which is promising for potential applications of integrated topotronic and ferroelectric devices.