Trivial topological phase of CaAgP and the topological nodal-line transition in CaAg(P1-xAsx)

TL;DR

This study combines experimental and theoretical methods to show that CaAgP is a trivial insulator, but can transition into a topological nodal-line semimetal through pressure or chemical substitution.

Contribution

It demonstrates the topological phase transition in CaAg(P1-xAsx) via pressure and substitution, revealing a pathway to realize topological nodal-line semimetals.

Findings

CaAgP is topologically trivial with a large bandwidth surface state.

Negative hydrostatic pressure can induce a topological phase transition.

Partial P/As substitution at x=0.38 achieves the topological transition.

Abstract

By performing angle-resolved photoemission spectroscopy and first-principles calculations, we address the topological phase of CaAgP and investigate the topological phase transition in CaAg(P1-xAsx). We reveal that in CaAgP, the bulk band gap and surface states with a large bandwidth are topologically trivial, in agreement with hybrid density functional theory calculations. The calculations also indicate that application of "negative" hydrostatic pressure can transform trivial semiconducting CaAgP into an ideal topological nodal-line semimetal phase. The topological transition can be realized by partial isovalent P/As substitution at x = 0.38.