Department of Materials Science & Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA.
Nat Commun. 2014 Mar 17;5:3432. doi: 10.1038/ncomms4432.
The existence of 30 noncentrosymmetric metals (NCSM) suggests a contraindication between crystal structures without inversion symmetry and metallic behaviour. Those containing oxygen are especially scarce. Here we propose and demonstrate a design framework to remedy this property disparity and accelerate NCSM oxide discovery. The primary ingredient relies on the removal of inversion symmetry through displacements of atoms whose electronic degrees of freedom are decoupled from the states at the Fermi level. Density functional theory calculations validate this crystal-chemistry strategy, and we predict a new polar ruthenate exhibiting robust metallicity. We demonstrate that the electronic structure is unaffected by the inclusion of spin-orbit interactions, and that cation-ordered SrCaRu2O6 exhibits a large thermopower anisotropy (|ΔS⊥|6.3 μV K(-1) at 300 K) derived from its polar structure. Our findings provide chemical and structural selection guidelines to aid in the search of NCSM with enhanced thermopower anisotropy.
约 30 种非中心对称金属（NCSM）的存在表明，没有反演对称的晶体结构与金属行为之间存在矛盾。含氧量特别少。在这里，我们提出并证明了一个设计框架，以弥补这种性能差异并加速 NCSM 氧化物的发现。主要成分依赖于通过原子位移来去除反演对称性，这些原子的电子自由度与费米能级的状态解耦。密度泛函理论计算验证了这种晶体化学策略，我们预测了一种新的表现出稳定金属性的极性钌酸盐。我们证明了电子结构不受包括自旋轨道相互作用的影响，并且有序的 SrCaRu2O6 阳离子表现出大的热功率各向异性（在 300 K 时 |ΔS⊥|~6.3 μV K(-1)），源于其极性结构。我们的发现为增强热功率各向异性的 NCSM 提供了化学和结构选择指南。
