Normal Dirac Semimetal Phase and Zeeman-Induced Topological Fermi Arc in PtSr5

TL;DR

This study identifies PtSr5 as a normal Dirac semimetal with trivial topology and demonstrates that an external Zeeman magnetic field can induce a transition to a Weyl semimetal phase, showcasing tunable topological properties.

Contribution

The paper reveals that PtSr5 hosts a trivial Dirac semimetal phase and can be transformed into a Weyl semimetal through an external magnetic field, highlighting tunability of topological phases.

Findings

PtSr5 is a normal Dirac semimetal with trivial Z2 topology.

Applying a Zeeman magnetic field induces a Weyl semimetal phase.

External perturbations can control topological states in PtSr5.

Abstract

Pt-Sr binary intermetallics encompass a broad range of stoichiometries and crystal structures, stabilized by complex bonding and multivalent chemistry. The Sr-rich end member, PtSr5, is recently identified via artificial-intelligence-guided materials design as a body-centered tetragonal compound (I4/m). Using first-principles calculations, we show that PtSr5 hosts a Dirac semimetal phase with trivial Z2 topology, classified as a normal Dirac semimetal. A symmetry-indicator analysis based on parity eigenvalues at the eight time-reversal-invariant momenta confirms that all Z2 invariants-evaluated on time-reversal-invariant two-dimensional subspaces of momentum space with a direct band gap-are trivial, thereby establishing the topologically trivial nature of the Dirac semimetal phase. Nonetheless, our calculations reveal that applying an external Zeeman magnetic field along the z-axis drives the system into a Weyl semimetal phase, as corroborated by characteristic changes in the computed surface states. This work demonstrates the tunability of topological phases in PtSr5 via external perturbations and highlights the effectiveness of AI-based materials exploration in discovering new quantum materials.