A STUDY OF TOPOLOGICAL PHASE TRANSITION IN RARE-EARTH MATERIAL YTTRIUM PHOSPHIDE

Abstract

In this work, we explore the topological quantum phase transitions in Yttrium Phosphide (YP) under varying hydrostatic pressures using first-principles calculations based on density functional theory and the Green’s function approach. At ambient conditions, YP crystallizes in a rock-salt cubic structure and exhibits metallic character. To examine the pressure-driven behaviour, we studied its structural, mechanical, dynamical, electronic, and topological properties at ambient as well as applied hydrostatic pressure. The compound is found to be both mechanically and dynamically stable, as confirmed by its elastic constants and phonon dispersion curves. A pressure-induced structural phase transition is observed at 63.6 GPa, accompanied by a discontinuity in enthalpy and volume, suggesting a transition from the cubic to a tetragonal structure. The band structure analysis reveals a band inversion near the Fermi level under increasing pressure, a signature of non-trivial topological behaviour. To confirm this transition, we calculated the ℤ₂ invariant through the evolution of Wannier charge centers, which confirms a topological phase transition at high pressure. These findings provide valuable insight into the pressure-tuneable topological properties of monopnictide materials and highlight YP as a promising candidate for future quantum material applications.