Magnetic topological insulators at finite temperature

Area of Science:

• Condensed matter physics
• Materials science
• Quantum mechanics

Background:

• Topological insulators (TIs) are materials with unique electronic properties, exhibiting insulating bulk and conducting surface states.
• Magnetic topological insulators (MTIs) integrate magnetic order with topological properties, leading to novel phenomena.
• Correlated topological insulators involve strong electron-electron interactions, complicating their phase diagrams and properties.

Purpose of the Study:

• To investigate the emergence of magnetic topological insulators (MTIs) in two-dimensional (2D) correlated Chern insulators and correlated Z2 topological insulators at finite temperatures.
• To determine the influence of thermal fluctuations on the topological and magnetic properties of these systems.
• To elucidate the fundamental differences in the thermal response between correlated Chern and Z2 topological insulators.

Main Methods:

• Utilizing theoretical modeling and numerical simulations to analyze the behavior of 2D correlated topological insulators.
• Examining the effects of finite temperature and thermal fluctuations on the electronic band structure and magnetic ordering.
• Comparing the phase diagrams and stability of magnetic topological insulator phases in different correlated systems.

Main Results:

• A thermal-fluctuation-induced magnetic topological insulator (MTI) phase is identified in the intermediate interaction regime of the 2D correlated Chern insulator.
• Conversely, the correlated Z2 topological insulator does not exhibit a thermal-fluctuation-induced MTI phase.
• Distinct mechanisms governing the emergence of MTI states in the two types of correlated topological insulators were revealed.

Conclusions:

• The presence or absence of thermal-fluctuation-induced MTI phases depends critically on the underlying topological classification (Chern vs. Z2) and electron correlation strength.
• Finite temperature effects can stabilize or destabilize topological phases, offering a route to tune material properties.
• Understanding these distinctions is crucial for designing novel quantum materials with tailored magnetic and topological functionalities.