Topological phase transition associated with structural phase transition in ternary half Heusler compound LiAuBi.

In this article, we report detailed theoretical investigations of topological phases in non-centrosymmetric half Heusler compound LiAuBi up to a pressure of 30 GPa. It is found that the compound forms into a dynamically stable face-centered cubic (FCC) lattice structure of space groupF4¯3m(216) at ambient pressure. The compound is topologically non-trivial at ambient pressure, but undergoes a quantum phase transition to trivial topological phase at 23.4 GPa. However, the detailed investigations show a structural phase transition from FCC lattice (space group 216) to a honeycomb lattice (space group 194) at 13 GPa, which is also associated with a non-trivial to trivial topological phase transition. Further investigations show that the compound also carries appreciable thermoelectric properties at ambient pressure. The figure of merit ( ZT ) increases from 0.21 at room temperature to a maximum value of 0.22 at 500 K. The theoretical findings show its potential for practical applications in spintronics as well as thermoelectricity, therefore LiAuBi needs to be synthesized and investigated experimentally for its applications.