<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Ta</mml:mi><mml:mn>4</mml:mn></mml:msub><mml:mi>CoSi</mml:mi></mml:mrow></mml:math>: A tantalum-rich superconductor with a honeycomb network structure
Lingyong Zeng, Xunwu Hu, Shu Guo, Gaoting Lin, Jing Song, Kuan Li, Yiyi He, Yanhao Huang, Chao Zhang, Peifeng Yu, Jie Ma, Dao‐Xin Yao, Huixia Luo
Abstract
The crystal structure of solid-state materials with unique lattices is considered one of the main factors determining physical properties, including superconductivity. Materials with honeycomb lattices have inspired intense research interest for their novel properties. A previously unknown compound, ${\mathrm{Ta}}_{4}\mathrm{CoSi}$, is discussed herein, along with its crystal structure and superconducting properties. It crystallizes in a $\mathrm{Cu}{\mathrm{Al}}_{2}\text{\ensuremath{-}}\mathrm{type}$ structure (space group P4/mcc, No. 124), with the lattice parameters $a=b=6.17755(7)\phantom{\rule{0.16em}{0ex}}\AA{}$ and $c=4.98443(8)\phantom{\rule{0.16em}{0ex}}\AA{}$, featuring honeycomb networks of Ta-Ta in the (110) plane. Superconductivity is observed below the critical temperature of \ensuremath{\sim}2.45 K, while lower and upper critical magnetic fields are \ensuremath{\sim}9.86 mT and 0.84 T, respectively. Experiments and theoretical calculations show that the honeycomb lattices significantly influence the superconducting properties. This material may thus provide a new platform for investigating the exotic superconductivity of honeycomb networks.