Two-gap and three-gap superconductivity in AlB2-based films
Two-gap and three-gap superconductivity in AlB2-based films
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AlB2 基薄膜中的两带隙和三带隙超导性
DOI：
10.1103/physrevb.100.094516
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发表时间：
2019
影响因子：
3.7
通讯作者：
Ni Jun
中科院分区：
文献类型：
--
作者：
Zhao Yinchang;Lian Chao;Zeng Shuming;Dai Zhenhong;Meng Sheng;Ni Jun
与超导相比，由于在中硼的共价态驱动下缺乏金属化，所以同结构没有超导性。本文从第一性原理出发，研究了超薄极限下的超导行为，揭示了相变温度范围为的双间隙超导性质。我们的研究结果表明，薄膜中的超导性主要来源于表面硼平面驱动的共价态，这种共价态由于量子约束而越过费米能级。因此，具有表面硼层存在于系统两侧的高化学计量膜也承诺令人钦佩的超导性。特别是，具有令人兴奋的三间隙性质的高被捕获在具有化学计量和三明治结构的最薄薄膜中。此外，还研究了外部应变对最薄薄膜和夹层薄膜超导行为的影响，结果表明，在双轴拉伸应变为的情况下，较小的压缩应变可以进一步促进最薄薄膜和夹层薄膜的超导行为，并且在最薄薄膜上也可以观察到三间隙性质。这些发现不仅为研究超导基材料铺平了道路，也为寻找多间隙超导体铺平了道路。
In contrast tosuperconducting at, the isostructuralhas no superconductivity due to the absence of metallization driven by the covalent state of boron in. In this paper, we investigate from first principles the superconducting behavior in ultrathin limit of, and reveal a two-gap superconducting nature with transition temperaturesin the range of. Our results indicate that the superconductivity infilms originates mainly from the surface-boron-plane-driven covalent state which crosses the Fermi level because of the quantum confinement. Therefore, the hyperstoichiometricfilms with the surface boron layer existing on each side of the systems also promise admirable superconductivity. In particular, a highwith an exciting three-gap nature is captured in the thinnestfilms that possess a stoichiometry ofand a sandwich configuration of. In addition, the effect of external strain on superconducting behavior in the thinnestfilm and sandwichfilm is also involved, which shows that a small compressive strain can further boost thein both films and a three-gap nature can be also observed in the thinnestfilm under a biaxial tensile strain of. These findings pave the way not only for study of superconductivity in-based materials but also the search for multigap superconductors.