Quantum oscillation studies in ferromagnetic Mn(Bi_1-xSb_x)₄Te₇

The magnetic topological materials family MnBi_2nTe_3n+1 provide a unique platform to study the interplay between magnetism and topology. Their great tunability with the structure (by modifying n), chemical doping (with Sb, Pb etc.), and dimensionality (bulk to thin-film device) gives rise to capability to host rich variations of topological states and magnetic structures, paving ways to emergent physics such as quantum anomalous Hall effect and axion insulators. We report our growths and Shubnikov–de Haas oscillation studies on bulk Mn(Bi_1-xSb_x)₄Te₇ (0.25<x<0.31) crystals with ferromagnetic ground state, which have been predicted to host different topological states including Axion insulator, Weyl semimetal, and topological crystalline insulator. Using Sb doping to introduce ferromagnetism to the ground state, and to fine-tune the carrier from electron to hole, we map out the evolution of the Fermi surface near the charge neutrality point, shedding light on the effect of magnetism on the bands structure of this system.