MoP在高压下的电子,声子和电声耦合性质的第一性原理计算

First-principles calculation of electron,phonon and electroacoustic coupling properties of MoP under high pressure

使用第一性原理方法,研究了拓扑材料MoP在高压下的电子结构和晶格动力学行为.高压下MoP的晶体结构和费米面附近的电子能带相对稳定,但是声子能谱以及电声子耦合参数随着压强的增大有明显的变化.声子谱中高频光学支逐渐硬化,低频声学支中也有部分出现明显软化,体系的电声子耦合随压强的增大而逐步变强,导致超导转变温度从常压下的零提高到30 GPa时的0.16 K,最后在50 GPa时提高到1.21 K,与实验的变化趋势基本一致.研究揭示了高压下MoP中出现的超导现象主要是电声子耦合造成的,为理解实验观测到的拓扑超导共存现象提供了一定的理论支持.

The electronic structure and lattice dynamics of MoP under high pressure were studied by first-principles method.The crystal structure of MoP under high pressure and the electron energy band near Fermi surface are relatively stable,but the phonon energy spectrum and electro-phonon coupling parameters change significantly with the increase of pressure.In the phonon spectrum,the high-frequency optical branch is gradually hardened,and some of the low-frequency acoustic branches are obviously softened.The electro-phonon coupling of the system gradually becomes stronger with the increase of the pressure,which causes the superconducting transition temperature to increase from 0 K under normal pressure to 0.16 K at 30 GPa,and finally increased to 1.21 K at 50 GPa,which is basically consistent with the trend of the experiment.The research reveals that the superconductivity appearing in MoP under high pressure is mainly caused by electro-phonon coupling,which provides some theoretical support for understanding the observed coexistence of topological superconductivity.