Unconventional Pressure-Driven Metamagnetic Transitions in Topological van der Waals Magnets

Recent progress in MnBi2nTe3n+1 intrinsic magnetic topological insulators: crystal growth, magnetism and chemical disorder

The search for magnetic topological materials has been at the forefront of condensed matter research for their potential to host exotic states such as axion insulators, magnetic Weyl semimetals, Chern insulators, etc. To date, the MnBi2nTe3n+1 family is the only group of materials showcasing van der Waals-layered structures, intrinsic magnetism and non-trivial band topology without trivial bands at the Fermi level. The interplay between magnetism and band topology in this family has led to the proposal of various topological phenomena, including the quantum anomalous Hall effect, quantum spin Hall effect and quantum magnetoelectric effect. Among these, the quantum anomalous Hall effect has been experimentally observed at record-high temperatures, highlighting the unprecedented potential of this family of materials in fundamental science and technological innovation. In this paper, we provide a comprehensive review of the research progress in this intrinsic magnetic topological insulator family, with a focus on single-crystal growth, characterization of chemical disorder, manipulation of magnetism through chemical substitution and external pressure, and important questions that remain to be conclusively answered.

Relationship between Antisite Defects, Magnetism, and Band Topology in MnSb2Te4 Crystals with TC ≈ 40 K

MnSb₂Te₄ has attracted extensive attention because of its rich and adjustable magnetic properties. Here, using a modified crystal growth method, ferrimagnetic MnSb₂Te₄ crystals with enhanced Curie temperature (T_C) of about 40 K with dominant hole-type carriers and intrinsic anomalous Hall effect is obtained. Time- and angle-resolved photoemission spectroscopy reveals that surface states are absent in both antiferromagnetic and ferrimagnetic MnSb₂Te₄, implying that they have topologically trivial electronic structures. We propose that the enhancement of ferrimagnetism mainly originates from the increase of intralayer magnetic coupling caused by the decrease of Sb content at Mn sites when the decrease of Mn concentration at Sb sites would prefer the nontrival band topology. Moreover, it is known that the initial saturation moment (M_is) is sensitive to the concentrations of Mn/Sb antisite defects; thus, the M_is could be a valuable parameter to evaluate the magnetic and topological properties of MnX_2nTe_3n+1 (X = Bi, Sb) families.