A topological insulator is a material that behaves as an insulator in the bulk but shows exotic conducting states on its surface which are protected by the time-reversal symmetry. The interplay of magnetism and topology is a key research subject in condensed matter physics, which offers great opportunities to explore emerging new physics, such as the quantum anomalous Hall effect, axion electrodynamics, and Majorana fermions. As a new extension of the current study of topological insulators, antiferromagnetic topological insulators (AFMTI), in which the antiferromagnetic long-range order in a topological insulator spontaneously breaks time-reversal symmetry. Proposed by most cutting-edge research, MnBi2Te4, GdBiPt are two promising examples of this topological class. The…

A hot topic in condensed matter physics in recent years is related to the quantum spin liquid (QSL) state, in which strong quantum fluctuations prevent spins from ordering or freezing and they remain in a disordered liquid-like states even at absolute zero. Previous studies have shown that QSL state tends to emerge in the geometrically frustrated systems with two-dimensional low-spin magnetic lattices, in which the interactions among the limited magnetic degrees of freedom is restricted by crystal geometry. When Ising spins are placed on a lattice with triangular motifs (a), AFM interactions cannot be simultaneously satisfied for all positions, therefore leading to the “frustration” of the system. This is called…