NbP中压力诱导的Lifshitz转变:Raman,X射线衍射,电输运和密度泛函理论
Pressure-induced Lifshitz transition in NbP: Raman, x-ray diffraction, electrical transport and density functional theory
摘要:
我们报告的高压拉曼,同步X射线衍射和电输运的Weyl半金属铌磷和钽的研究与第一性原理密度泛函理论(DFT)分析。NbP的一阶拉曼模式的频率硬化与压力的增加,并表现出一个斜率的变化在P $_c$ $\sim$ 9 GPa,其电阻率表现出最小值在P $_c$。在P $_c$处,NbP的体积模量随压力变化,从207 GPa变化到243 GPa。使用DFT计算,我们表明,这些异常与压力诱导的Lifshitz转变,其中涉及的电子和空穴口袋在其电子结构的外观。与此相反,TaP和DFT计算的拉曼和同步X射线衍射实验的结果表明,TaP是相当强大的压力下,不进行任何相变。
英文摘要:
We report high pressure Raman, synchrotron x-ray diffraction and electrical transport studies on Weyl semimetals NbP and TaP along with first-principles density functional theoretical (DFT) analysis. The frequencies of first-order Raman modes of NbP harden with increasing pressure and exhibit a slope change at P$_c$ $\sim$ 9 GPa, and its resistivity exhibits a minimum at P$_c$. The pressure-dependent volume of NbP exhibits a change in its bulk modulus from 207 GPa to 243 GPa at P$_c$. Using DFT calculations, we show that these anomalies are associated with pressure induced Lifshitz transition which involves appearance of electron and hole pockets in its electronic structure. In contrast, results of Raman and synchrotron x-ray diffraction experiments on TaP and DFT calculations show that TaP is quite robust under pressure and does not undergo any phase transition.
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