Broken Symmetry-driven Weyl Semimetal Phase in Zn-Substituted EuMn$_2$Sb$_2$

TL;DR

Zn substitution in EuMn$_2$Sb$_2$ induces a transition from an antiferromagnetic semiconductor to a magnetic Weyl semimetal, demonstrating how chemical tuning can engineer topological quantum phases in correlated materials.

Contribution

This work reveals that chemical substitution can transform EuMn$_2$Sb$_2$ into a magnetic Weyl semimetal, highlighting a new route to control topology via magnetism in correlated electron systems.

Findings

Zn substitution stabilizes ferromagnetism in EuMn$_2$Sb$_2$.

Weyl nodes emerge near the Fermi level due to broken symmetries.

EuMnZnSb$_2$ hosts topologically protected Fermi-arc surface states.

Abstract

The interplay between magnetism and electronic topology offers a powerful route to realizing emergent quantum phases. Here, we show that Zn substitution in the layered compound EuMn$_2$Sb$_2$ drives a transition from a C-type antiferromagnetic semiconductor to an intrinsic magnetic Weyl semimetal. Using first-principles calculations, we demonstrate that the parent compound hosts a gapped antiferromagnetic ground state, while Zn substitution alters the magnetic exchange interactions and stabilizes ferromagnetism. In the spin-orbit-coupled regime, the coexistence of broken time-reversal ($\mathcal{T}$) and inversion ($\mathcal{P}$) symmetries leads to the formation of Weyl nodes near the Fermi level. These nodes act as monopoles of Berry curvature and give rise to topologically protected Fermi-arc surface states. Our results identify EuMnZnSb$_2$ as a tunable platform where magnetism and topology are intrinsically coupled and establish chemical substitution as a viable strategy to engineer magnetic Weyl semimetals in correlated electron systems, with potential implications for spintronic and topological transport phenomena.