Ferromagnetism and anomalous Hall effect in MnBi₆Te₁₀

The (MnBi₂Te₄)(Bi₂Te₃)_m (m=0, 1, 2, &3) system provides a rich platform for the study of various exotic quantum states, such as axion insulator (AI) and quantum anomalous Hall insulator (QAHI). With m increasing, the strength of interlayer magnetic exchange interaction gradually weakens. Previous studies have shown the magnetic state of this system changes from antiferromagnetic (AFM) orders for m=0, 1 and 2 to a ferromagnetic order (FM) for m=3. The m=2 member, MnBi₆Te₁₀ exhibits enhanced competition between AFM and FM coupling, and a FM order has been reported to be accessible via 30% Sb substitution for Bi [1]. In this talk, we report the successful growth of FM Mn(Bi_1-xSb_x)₆Te₁₀ (x = 0, 0.08, 0.12, 0.3) crystals. Some samples exhibit a large remnant magnetization (2.7 μ_B/Mn). Our experiments also reveal a large anomalous Hall effect for the x=0.3 sample; its anomalous Hall resistivity is ~ 10 μΩ cm, about 10 times larger than that previously reported value for the AFM MnBi₆Te₁₀. These FM compounds could be promising candidates for realizing the QAHI and AI.

Reference:
[1] J. Wu, F. Liu, C. Liu, Y. Wang, C. Li, Y. Lu, S. Matsuishi, and H. Hosono, Adv. Mater. 32, 2001815 (2020).