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

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.

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

Abstract: 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 0k under normal pressure to 0.16k at 30 GPa, and finally increased to 1.21K 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 superconducting superconductivity phenomenon.