论文标题
2D原骨MB6（M = MG，CA）和Hexagonal MB6（M = MG，CA，CA，SC，TI，TI，SR，Y）中的电子偶联超导性超导性
Electron-phonon coupling superconductivity in 2D orthorhombic MB6 (M=Mg, Ca) and hexagonal MB6 (M=Mg, Ca, Sc, Ti, Sr, Y)
论文作者
论文摘要
结合晶体结构搜索和第一原理计算，我们报告了一系列二维（2D）金属硼，包括原骨（ORT-）MB6（M = mg，CA）和Hexagonal（Hex-）MB6（M = mg，Ca，Ca，Ca，ca，ca，ca，ca，ca，ca，sc，sc，sc，ti，ti，sr，y）。然后，我们研究了它们的几何结构，键合特性，电子结构，机械性能，声子分散，热稳定性，动态稳定性，电子 - 音波耦合（EPC），超导性能等。我们的从头算分子动力学仿真结果表明，这些MB6可以保持其原始配置高达700/1000 K，这表明它们出色的热稳定性。它们的所有弹性常数都满足了天生的机械稳定标准，并且在声子分散体中未观察到可见的假想频率。 EPC结果表明，这2D MB6都是固有的声子介导的超导体，其超导转换温度（TC ??）在2.2-21.3 K范围内，其中最高的TC（21.3 K）出现在Hex-CAB6中，Hex-Cab6的EPC常数为0.94。通过在ORT-/HEX-CAB6上施加拉伸/压缩应变，我们发现压缩应变显然可以软化声音子分支并增强EPC和TC。在3％的压缩应力下，十六进制-CAB6的TC可以从21.3 K增加到28 K。这些发现富含2D超导体的数据库，并应刺激2D超导金属硼化物的实验合成和表征。
Combining crystal structure search and first-principles calculations, we report a series of two-dimensional (2D) metal borides including orthorhombic (ort-) MB6 (M=Mg, Ca) and hexagonal (hex-) MB6 (M=Mg, Ca, Sc, Ti, Sr, Y). Then, we investigate their geometrical structures, bonding properties, electronic structures, mechanical properties, phonon dispersions, thermal stability, dynamic stability, electron-phonon coupling (EPC), superconducting properties and so on. Our ab initio molecular dynamics simulation results show that these MB6 can maintain their original configurations up to 700/1000 K, indicating their excellent thermal stability. All their elastic constants satisfy the Born mechanically stable criteria and no visible imaginary frequencies are observed in their phonon dispersions. The EPC results show that these 2D MB6 are all intrinsic phonon-mediated superconductors with the superconducting transition temperature (Tc??) in the range of 2.2-21.3 K. Among them, the highest Tc (21.3 K) appears in hex-CaB6, whose EPC constant () is 0.94. By applying tensile/compressive strains on ort-/hex-CaB6, we find that the compressive strain can obviously soften the acoustic phonon branch and enhance the EPC as well as Tc. The Tc of the hex-CaB6 can be increased from 21.3 K to 28 K under compressive strain of 3%. These findings enrich the database of 2D superconductors and should stimulate experimental synthesizing and characterizing of 2D superconducting metal borides.
