Higher-order topological Mott insulator on the pyrochlore lattice

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Topological Phases of Matter

Background:

• Topological insulators exhibit unique electronic properties protected by topology.
• Higher-order topological insulators possess protected boundary states at lower dimensions.
• Mott insulators are characterized by strong electron-electron interactions.

Purpose of the Study:

• To provide the first unbiased evidence for a three-dimensional higher-order topological Mott insulator.
• To characterize the gapless modes and phase transitions in this novel correlated topological phase.

Main Methods:

• Numerically exact quantum Monte Carlo simulations.
• Adiabatic connection to non-interacting topological insulator limit.
• Analysis of spin-Berry phase and bulk spin gap.

Main Results:

• Identification of a higher-order topological Mott insulator in three dimensions.
• Discovery of Mott-like gapless corner modes emerging in spin excitations.
• Characterization of the topological phase transition driven by bulk spin gap closure.

Conclusions:

• The existence of three-dimensional higher-order topological Mott insulators is confirmed.
• Correlated topological phases exhibit distinct phenomena, such as spin-excitation-localized corner modes.
• The bulk spin gap closing serves as the critical point for phase transitions.