Magnetic topological insulator in MnBi6Te10 with zero-field ferromagnetic state

Magnetic topological insulator with nontrivial topological electronic structure and broken time-reveal symmetry exhibits various exotic topological quantum phenomena, like quantum anomalous Hall effect (QAHE) and axion insulator state. The realization of such exotic phenomena at high temperature is one of central topics in this area. Here, combined with experimental measurements and theoretical calculations, we reveal that MnBi6Te10 is a strong TI with Dirac surface states at paramagnetic state and it evolves into an antiferromagnetic TI below 10.8 K. More importantly, the ferromagnetic axion insulator state emerges once spins polarized at field as low as 0.1 T, accompanied with saturated anomalous Hall resistivity up to 10 K. At 2 K, such state is preserved even external field down to zero. Furthermore, our calculations indicate that the few-layer ferromagnetic MnBi6Te10 have a non-zero Chern number. These outstanding features suggest MnBi6Te10 is a promising system to realize axion electrodynamics effects and high-temperature QAHE.