Meng Jingjing, Zheng Pengyu, Peng Yiran, Liu Rui, Yang Ying, Yin Zhiping
Department of Physics, Center for Advanced Quantum Studies, Beijing Normal University Beijing 100875 China
Key Laboratory of Multiscale Spin Physics, Ministry of Education, Beijing Normal University Beijing 100875 China.
RSC Adv. 2024 Apr 2;14(15):10507-10515. doi: 10.1039/d3ra08746h. eCollection 2024 Mar 26.
With extensive structure searches for XB (X = Sc, Ti, V, Cr, and Tc) under pressures up to 100 GPa, we uncovered that the crystal structures of these compounds with the lowest enthalpy have the same space group (6/) as MgB at ambient pressure. Among them, ScB, TiB and VB are dynamically stable at ambient pressure, but they do not superconduct. CrB becomes dynamically stable at 108 GPa and shows superconductivity with a transition temperature () of 26.0 K. TcB is not dynamically stable until 9 GPa. At 20 GPa, it has a of 23.5 K. Further calculations indicate that CrB and TcB are also thermodynamically stable, suggesting that it is highly likely that they can be synthesized successfully in the laboratory. We found that transition metal atoms (Cr/Tc) dominate soft phonon vibrations and make significant contributions to the electron-phonon coupling (EPC) and superconductivity in CrB/TcB, which is in strong contrast to the case of MgB, where high-frequency B vibrations dominate the EPC and superconductivity. Our work enriches the understanding of superconductivity in transition metal borides.
通过在高达100 GPa的压力下对XB（X = Sc、Ti、V、Cr和Tc）进行广泛的结构搜索，我们发现这些具有最低焓值的化合物的晶体结构在常压下与MgB具有相同的空间群（6/）。其中，ScB、TiB和VB在常压下是动力学稳定的，但它们不超导。CrB在108 GPa时变得动力学稳定，并表现出超导性，转变温度（）为26.0 K。TcB直到9 GPa才动力学稳定。在20 GPa时，其为23.5 K。进一步的计算表明，CrB和TcB在热力学上也是稳定的，这表明它们很有可能在实验室中成功合成。我们发现过渡金属原子（Cr/Tc）主导软声子振动，并对CrB/TcB中的电子 - 声子耦合（EPC）和超导性做出重大贡献，这与MgB的情况形成强烈对比，在MgB中高频B振动主导EPC和超导性。我们的工作丰富了对过渡金属硼化物中超导性的理解。
