Manipulation of topological phase transitions and the mechanism of magnetic interactions in Eu-based Zintl-phase materials

TL;DR

This paper explores methods to control topological phase transitions in Eu-based Zintl materials through electron correlation and electronegativity adjustments, linking magnetic interactions with topological states for potential spintronics and quantum computing applications.

Contribution

It introduces two novel approaches for manipulating topological phases in EuM$_2$X$_2$ materials and establishes a magnetic interaction model consistent with experimental data.

Findings

Electron correlation effects induce topological state transitions.

Reducing electronegativity promotes topological phases.

Monte Carlo simulations match experimental Néel temperatures.

Abstract

Various topological phases, including topological insulators, topological semimetals, and topological superconductors, along with the controllable topological phase transitions, have attracted considerable attention due to their promising applications in spintronics and quantum computing. In this work, we propose two distinct methods for manipulating topological phase transitions in magnetic materials. First, by varying the strength of electron correlation effects, we induce a series of topological state transitions within the EuM$_2$X$_2$ (M = Zn, Cd; X = P, As, Sb) family of Zintl materials, including magnetic topological crystalline insulators (TCIs) and magnetic Dirac semimetals. Our findings indicate that strong electron correlation effects tend to influence the emergence of topological phases. Second, by reducing the electronegativity of the pnictogen X (from P to As and Sb), we observe a similar transition from trivial insulator to magnetic Dirac semimetal or magnetic TCI. This suggests that weaker electronegativity favors the emergence of topological phases. Furthermore, we establish a Heisenberg model to describe the magnetic interactions of the EuM$_2$X$_2$ system, based on which we perform Monte Carlo simulations of specific heat and magnetic susceptibility, yielding N\'eel temperatures that perfectly match experimental data. This suggests that the local magnetic moment framework provides an accurate description of the magnetization behavior in this family of materials. This work provides the potential for the experimental manipulation of topological phase transitions and their possible applications, while also enhancing the understanding of the magnetic interactions within the EuM$_2$X$_2$ system and offering a theoretical foundation for future applications in magnetism.