Using the universal structure predictor algorithm, we proposed that two-dimensional MnB structures with p4mmm (α-MnB) and pmma (β-MnB) symmetries could be synthesized. This finding was verified by calculating the dynamical stability, molecular dynamics, and mechanical properties. The α-MnB had an in-plane stiffness Yx (=Yy) around 100 N/m while the β-Mn displayed an asymmetric mechanical stiffness of Yx = 186 N/m and Yy = 139 N/m. Both systems displayed a ferromagnetic ground state with metallic band structures. The calculated magnetic moments were 2.14 and 2.34 µB per Mn-B pair in the α-MnB and β-MnB. Furthermore, we investigated the potential superconductivity. In the α-MnB, we found the unique feature of Kohn anomaly at q~2kF in the diagonal direction of the Brillouin zone. The β-MnB phonon spectra showed a valley of degenerated localized softening vibration modes at the edge of the Brillouin zone. The ZA and LA phonon branches in this valley induced the largest contribution to electron-phonon coupling strength. The calculated total electron-phonon coupling parameters were 1.20 and 0.89 in α-MnB and β-MnB systems. Overall, we predict that the α-MnB and β-MnB systems can display 2D ferromagnetic superconducting states with the estimated critical temperatures of Tc ≈ 10−13 K.
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机译：利用通用结构预测器算法，我们可以合成具有p4mmm（α-MnB）和pmma（β-MnB）对称性的二维MnB结构。通过计算动力学稳定性，分子动力学和机械性能验证了这一发现。 α-MnB的面内刚度Yx（= Yy）约为100 N / m，而β-Mn的不对称机械刚度为Yx of = 186 N / m和Yy = 139 N / m。两种系统均显示具有金属能带结构的铁磁基态。在α-MnB和β-MnB中，每对Mn-B对的计算磁矩为2.14和2.34 µB。此外，我们研究了潜在的超导性。在α-MnB中，我们在布里渊区的对角线方向上在q〜2kF处发现了Kohn异常的独特特征。 β-MnB声子谱在布里渊区的边缘显示了一个退化的局部软化振动模态的谷。该谷中的ZA和LA声子支链对电子-声子耦合强度的贡献最大。在α-MnB和β-MnB系统中，计算的总电子-声子耦合参数为1.20和0.89。总的来说，我们预测α-MnB和β-MnB系统可以显示2D铁磁超导状态，其估计临界温度为Tc≈10-13K。
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