Gui Xin, Górnicka Karolina, Chen Qiang, Zhou Haidong, Klimczuk Tomasz, Xie Weiwei
Department of Chemistry, Louisiana State University (LSU), Baton Rouge, Louisiana 70803, United States.
Faculty of Applied Physics and Mathematics, Gdansk University of Technology (GUT), Narutowicza 11/12, Gdansk 80-233, Poland.
Inorg Chem. 2020 May 4;59(9):5798-5802. doi: 10.1021/acs.inorgchem.9b03656. Epub 2020 Apr 20.
The metal-metal bond in metal-rich chalcogenide is known to exhibit various structures and interesting physical properties. TaSe can be obtained by both arc-melting and solid-state pellet methods. TaSe crystallizes a layered tetragonal structure with space group 4/ (No. 129; Pearson symbol 6). Each unit cell consists of four layers of body-centered close-packing Ta atoms sandwiched between two square nets of Se atoms, forming the Se-Ta-Ta-Ta-Ta-Se networks. Herein, we present magnetic susceptibility, resistivity, and heat capacity measurements on TaSe, which together indicate bulk superconductivity with = 3.8(1) K. According to first-principles calculations, the d orbitals in Ta atoms dominate the Fermi level in TaSe. The flat bands at the Γ point in the Brillouin zone yield the van Hove singularities in the density of states around the Fermi level, which is intensified by introducing a spin-orbit coupling effect, and thus could be critical for the superconductivity in TaSe. The physical properties, especially superconductivity, are completely different from those of Ta-rich alloys or transition-metal dichalcogenide TaSe.
富金属硫族化合物中的金属-金属键已知具有多种结构和有趣的物理性质。TaSe可以通过电弧熔炼和固态压块法获得。TaSe结晶形成具有空间群4/（编号129；皮尔逊符号6）的层状四方结构。每个晶胞由四层位于体心密堆积的Ta原子夹在两层Se原子的方形网之间组成，形成Se-Ta-Ta-Ta-Ta-Se网络。在此，我们展示了对TaSe的磁化率、电阻率和热容量测量结果，这些结果共同表明其体超导性，超导转变温度(T_c = 3.8(1) K)。根据第一性原理计算，Ta原子中的d轨道在TaSe中主导费米能级。布里渊区Γ点处的平带在费米能级附近的态密度中产生范霍夫奇点，通过引入自旋轨道耦合效应使其增强，因此这可能是TaSe超导性的关键因素。其物理性质，尤其是超导性，与富Ta合金或过渡金属二硫属化物TaSe完全不同。
