Novel electronic properties of monoclinic MP4 (M = Cr, Mo, W) compounds with or without topological nodal line

Abstract

AbstractTransition metal phosphides hold novel metallic, semimetallic, and semiconducting behaviors. Here we report by ab initio calculations a systematical study on the structural and electronic properties of $$\hbox {MP}_4$$MP4 (M = Cr, Mo, W) phosphides in monoclinic C2/c ($$C_{2h}^6$$C2h6) symmetry. Their dynamical stabilities have been confirmed by phonon modes calculations. Detailed analysis of the electronic band structures and density of states reveal that $$\hbox {CrP}_4$$CrP4 is a semiconductor with an indirect band gap of 0.47 eV in association with the p orbital of P atoms, while $$\hbox {MoP}_4$$MoP4 is a Dirac semimetal with an isolated nodal point at the $$\Gamma$$Γ point and $$\hbox {WP}_4$$WP4 is a topological nodal line semimetal with a closed nodal ring inside the first Brillouin zone relative to the d orbital of Mo and W atoms, respectively. Comparison of the phosphides with group VB, VIB and VIIB transition metals shows a trend of change from metallic to semiconducting behavior from $$\hbox {VB-MP}_4$$VB-MP4 to VIIB-$$\hbox {MP}_4$$MP4 compounds. These results provide a systematical understandings on the distinct electronic properties of these compounds.