Study of Topology and Magnetism in Novel Quantum Systems using Magnetotransport and ARPES study

The interplay between nontrivial band topology and magnetism has led to the discovery of novel quantum states of matter, exemplified by phenomena like the quantum anomalous Hall effect (QAHE) and axion dynamics. In this study, we explore the electronic and magnetic properties of MnSb₈Te₁₃ [1] and MnSb₁₂Te₁₉ [2] magnetic topological insulators using magnetotransport, angle-resolved photoemission spectroscopy (ARPES), and density functional theory (DFT). MnSb₈Te₁₃ shows three ferromagnetic (FM) transitions, with resistivity indicating non-Fermi liquid behavior and a hole-dominated electronic structure. DFT suggests it is an FM TI with surface states sensitive to crystal termination, though weak ferromagnetism is observed due to Mn deficiencies. In contrast, MnSb₁₂Te₁₉ displays strong FM behavior with a transition at 18.7 K, along with the anomalous Hall effect and Shubnikov-de-Haas oscillations indicating Dirac fermions with a π Berry phase. These results emphasize the distinctive magnetism-topology interplay in these materials, making them promising for future studies and potential applications in spintronics and quantum devices.