Layer-Number-Dependent Antiferromagnetic and Ferromagnetic Behavior in MnSb_{2}Te_{4}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• MnBi_{2}Te_{4} is an intrinsic magnetic topological insulator with layer-dependent phases.
• MnSb_{2}Te_{4}, an isostructural material, exhibits both antiferromagnetic (AFM) and ferromagnetic (FM) states in bulk.
• Understanding layer-number-dependent magnetism in MnSb_{2}Te_{4} is key to exploring its topological properties.

Purpose of the Study:

• To investigate the magnetic properties of MnSb_{2}Te_{4} down to the single septuple layer (SL) limit.
• To reveal the layer-number-dependent magnetic behaviors in both AFM and FM states of MnSb_{2}Te_{4} flakes.
• To elucidate the underlying mechanisms governing these magnetic transitions.

Main Methods:

• Polar reflective magnetic circular dichroism (MCD) spectroscopy was employed.
• Systematic studies were conducted on MnSb_{2}Te_{4} flakes of varying layer numbers.
• Analysis involved the antiferromagnetic (AFM) linear-chain model.

Main Results:

• Both A-type AFM and FM behaviors were observed in MnSb_{2}Te_{4} down to the single SL limit.
• An odd-even layer-number effect was identified in AFM MnSb_{2}Te_{4} flakes.
• Even-SL flakes exhibited an additional surface spin-flop (SSF) transition and stabilized in a collinear state due to specific energy ratios.

Conclusions:

• The study reveals rich magnetic states in few-SL MnSb_{2}Te_{4} as a function of layer number, magnetic field, and temperature.
• The observed magnetic behaviors, including the SSF transition, provide insights into the interplay of anisotropy and interlayer interactions.
• These findings are crucial for advancing quantum transport studies in few-layer MnSb_{2}Te_{4} and exploring topological phenomena.