Structural Tuning Magnetism and Topology in a Magnetic Topological Insulator

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Quantum anomalous Hall insulators (QAHI) are typically fabricated by doping magnetic ions into topological insulator (TI) thin films like (Bi_{1 - x}Sb_x)₂Te₃ (BST).
• Magnetic ordering in these systems opens an exchange gap in topological surface states, enabling dissipationless edge channels crucial for QAHI functionality.
• The interplay between magnetic and electronic properties is mediated by the host TI's electronic states, creating a complex feedback loop.

Purpose of the Study:

• To investigate the electronic and magnetic response of a BST-based QAHI system under hydrostatic pressure.
• To explore the effects of structural tuning on the topological gap and magnetic ordering.
• To understand the potential of hydrostatic pressure as a control parameter for QAHI phase space.

Main Methods:

• Experimental application of hydrostatic pressure to BST-based QAHI thin films.
• Measurement of electronic transport properties to observe changes in the topological gap.
• First-principle calculations to complement experimental findings and elucidate underlying mechanisms.

Main Results:

• A systematic closure of the topological gap was observed under compressive strain induced by hydrostatic pressure.
• A simultaneous enhancement in the magnetic ordering strength was detected alongside the gap closure.
• Structural deformation was confirmed as a significant factor influencing both electronic and magnetic properties.

Conclusions:

• Hydrostatic pressure is an effective external stimulus for tuning the topological and magnetic properties of BST-based QAHIs.
• Structural deformation provides a pathway to navigate diverse topological phases and modify magnetism in these materials.
• This study highlights the potential for precise control over QAHI states through mechanical strain engineering.