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 Pc∼ 9 GPa, and its resistivity exhibits a minimum at Pc. The pressure-dependent volume of NbP exhibits a change in its bulk modulus from 207 GPa to 243 GPa at Pc. 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.
@article{arxiv.1709.09368,
title = {Pressure-induced Lifshitz transition in NbP: Raman, x-ray diffraction, electrical transport and density functional theory},
author = {Satyendra Nath Gupta and Anjali Singh and Koushik Pal and D. V. S. Muthu and C. Shekhar and Yanpeng Qi and Pavel G. Naumov and Sergey A. Medvedev and C. Felser and U. V. Waghmare and A. K. Sood},
journal= {arXiv preprint arXiv:1709.09368},
year = {2018}
}