Spin-Orientation-Dependent Topological States in Two-Dimensional Antiferromagnetic NiTl₂S₄ Monolayers

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Topological states of matter arise from nontrivial magnetic configurations, offering insights into material properties.
• Active control of spin orientation is crucial for studying topological states but is rare in 2D materials.

Purpose of the Study:

• To demonstrate spin-orientation-dependent topological states in a geometrically frustrated 2D antiferromagnet.
• To explore the potential of NiTl2S4 monolayer for realizing novel topological phenomena.

Main Methods:

• First-principles calculations were employed to investigate the electronic and magnetic properties of the NiTl2S4 monolayer.
• Spin orientation was systematically varied to identify different topological states.

Main Results:

• The NiTl2S4 monolayer exhibits tunable topological states, including the quantum anomalous Hall (QAH) effect and time-reversal-symmetry (TRS) broken quantum spin Hall (QSH) effect.
• A dilated nc-AFM NiTl2S4 monolayer shows the QAH effect with a record Chern number of -4.
• A novel state with coexisting QAH and TRS broken QSH effects was discovered under tunable chemical potential (Chern number = 3, spin Chern number = 1).

Conclusions:

• The study presents a promising concept for topological spintronics in 2D antiferromagnets by controlling spin orientation.
• The NiTl2S4 monolayer serves as a potential material platform for realizing advanced spintronic devices.