Strong-Coupling Superconductivity with $T_c$ $\sim$ 10.8 K Induced by P Doping in the Topological Semimetal Mo$_5$Si$_3$

Bin-Bin Ruan; Jun-Nan Sun; Yin Chen; Qing-Song Yang; Kang Zhao; Meng-Hu Zhou; Ya-Dong Gu; Ming-Wei Ma; Gen-Fu Chen; Lei Shan; Zhi-An Ren

doi:10.1007/s40843-022-2102-8

paper

Strong-Coupling Superconductivity with $T_{c}$ $\sim$ 10.8 K Induced by P Doping in the Topological Semimetal Mo $_{5}$ Si $_{3}$

arXiv:2208.02392 · doi:10.1007/s40843-022-2102-8

Abstract

By performing P doping on the Si sites in the topological semimetal Mo $_{5}$ Si $_{3}$ , we discover strong-coupling superconductivity in Mo $_{5}$ Si $_{3 - x}$ P $_{x}$ (0.5 $\leq$ $x$ $\leq$ 2.0). Mo $_{5}$ Si $_{3}$ crystallizes in the W $_{5}$ Si $_{3}$ -type structure with space group of $I 4/ m c m$ (No. 140), and is not a superconductor itself. Upon P doping, the lattice parameter $a$ decreases while $c$ increases monotonously. Bulk superconductivity is revealed in Mo $_{5}$ Si $_{3 - x}$ P $_{x}$ (0.5 $\leq$ $x$ $\leq$ 2.0) from resistivity, magnetization, and heat capacity measurements. $T_{c}$ in Mo $_{5}$ Si $_{1.5}$ P $_{1.5}$ reaches as high as 10.8 K, setting a new record among the W $_{5}$ Si $_{3}$ -type superconductors. The upper and lower critical fields for Mo $_{5}$ Si $_{1.5}$ P $_{1.5}$ are 14.56 T and 105 mT, respectively. Moreover, Mo $_{5}$ Si $_{1.5}$ P $_{1.5}$ is found to be a fully gapped superconductor with strong electron-phonon coupling. First-principles calculations suggest that the enhancement of electron-phonon coupling is possibly due to the shift of the Fermi level, which is induced by electron doping. The calculations also reveal the nontrivial band topology in Mo $_{5}$ Si $_{3}$ . The $T_{c}$ and upper critical field in Mo $_{5}$ Si $_{3 - x}$ P $_{x}$ are fairly high among pseudobinary compounds. Both of them are higher than those in NbTi, making future applications promising. Our results suggest that the W $_{5}$ Si $_{3}$ -type compounds are ideal platforms to search for new superconductors. By examinations of their band topologies, more candidates for topological superconductors can be expected in this structural family.

15 pages, 5 figures. Supplementary Information availabe at the corresponding DOI

Strong-Coupling Superconductivity with $T_{c}$ $\sim$ 10.8 K Induced by P Doping in the Topological Semimetal Mo $_{5}$ Si $_{3}$

Abstract

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Strong-Coupling Superconductivity with Tc​ ∼ 10.8 K Induced by P Doping in the Topological Semimetal Mo5​Si3​

Abstract

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Strong-Coupling Superconductivity with $T_{c}$ $\sim$ 10.8 K Induced by P Doping in the Topological Semimetal Mo $_{5}$ Si $_{3}$