Unexpected room-temperature ferromagnetism in nanostructured Bi2Te3

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Topological insulators are crucial for realizing the quantum anomalous Hall effect.
• Developing intrinsic magnetism in topological insulators is essential for advanced electronic applications.
• Bismuth telluride (Bi2Te3) is a prominent topological insulator material.

Purpose of the Study:

• To investigate the origin of magnetism in nanostructured topological insulator Bi2Te3.
• To explore the potential for room-temperature ferromagnetism without magnetic doping.
• To provide new insights into defect-induced magnetism in topological materials.

Main Methods:

• Experimental fabrication of nanostructured hierarchical architectures of Bi2Te3.
• Characterization of magnetic properties at room temperature.
• First-principles calculations to identify the source of magnetic moments.

Main Results:

• Intriguing room-temperature ferromagnetism was identified in Bi2Te3 nanostructures.
• Intrinsic point defects, specifically antisite Te defects, were found to be responsible for the magnetic moment.
• The mechanism differs from previously studied vacancy-induced magnetism.

Conclusions:

• Antisite defects in Bi2Te3 can intrinsically induce ferromagnetism.
• This discovery offers a new pathway for understanding magnetism in topological insulators.
• The findings support the development of Bi2Te3-based dissipationless spintronics and quantum computation.