Synthesis, physical properties, and band structure of the layered bismuthide PtBi2
Synthesis, physical properties, and band structure of the layered bismuthide PtBi2
复制标题
层状铋化物PtBi2的合成、物理性质及能带结构
DOI：
10.1103/physrevb.94.165119
复制
发表时间：
2016
影响因子：
3.7
通讯作者：
Z.X. Shi
中科院分区：
文献类型：
--
作者：
C.Q. Xu;X.Z. Xing;Xiaofeng Xu;B. Li;B. Chen;L.Q Che;Xin Lu;Jianhui Dai;Z.X. Shi
我们报道了化学计量铋化物PtBi2单晶生长的细节，其结构由Pt层和Bi双分子层沿c轴交替堆叠组成。该化合物在空间群P3中结晶，晶胞为六角形，a = b = 6.553埃，c = 6.165埃。它的t相关电阻率是典型的金属，而在面内和面间电传输中观察到很大的各向异性。平行于铂层和垂直于铂层的磁化数据显示相反的符号。这种材料的磁场响应清楚地显示出两种类型的载流子，与我们在能带结构计算中揭示的多重费米面一致。静水压力系统地抑制了高温度下的电阻率，但对低温度下的输运影响不大。通过量热测量，确定费米能级和德拜温度下的态密度分别为0.94 eV(-1) /分子和145 K /分子。此外，还介绍了其电子结构和宇称分析。通过调用自旋轨道相互作用，我们发现在费米能级下2ev左右有0.05 eV隙开的最小值。平板计算进一步表明，表面狄拉克锥出现在体态间隙。我们讨论了PtBi2作为块状拓扑金属的候选材料的可能性，类似于最近提出的拓扑超导体β - pdbi2。
We report details of single-crystal growth of stoichiometric bismuthide PtBi2 whose structure consists of alternate stacking of a Pt layer and Bi bilayer along the c axis. The compound crystallizes in space group P3 with a hexagonal unit cell of a = b = 6.553 angstrom, c = 6.165 angstrom. Its T-dependent resistivity is typical of a metal whereas a large anisotropy was observed for the in-plane and interplane electrical transport. The magnetization data show opposite sign for fields parallel and perpendicular to the Pt layers, respectively. Themagnetic field response of this material shows clearly two types of charge carriers, consistent with the multiple Fermi surfaces revealed in our band structure calculations. The hydrostatic pressure is shown to suppress the resistivity at high T systematically but has little bearing on its low-T transport. Through calorimetric measurements, the density of states at the Fermi level and the Debye temperature are determined to be 0.94 eV(-1) per molecule and 145 K, respectively. In addition, the electronic structures and parity analyses are also presented. We find a minimum value of 0.05 eV gap opening at around 2 eV under the Fermi level by invoking spin-orbit interaction. A slab calculation further indicates a surface Dirac cone appearing in the gap of bulk states. We discuss the possibility of PtBi2 being a candidate for a bulk topological metal, in analogy to the recently proposed topological superconductor beta-PdBi2.