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Highly tunable properties make the Mn(Bi,Sb)₂Te₄ phase diagram a rich playground for exploring the interplay between band topology and magnetism: On one end,  MnBi₂Te₄ (MBT) hosts axion insulator and Chern insulating states [1,2], while the band topology of Sb-substituted MnSb₂Te₄ (MST) is potentially sensitive to defect disorder [3]. In this work, we use magnetic force microscopy (MFM) to characterize the ferrimagnetic domains of MST. We find that an external magnetic field can be used to tune between distinct stripe and bubble domain morphologies. Moreover, the low coercive field makes it possible to manipulate domains with the MFM tip. With in-situ transport, we quantify the impact of individual domains on device properties. This work opens the door to writable domain-based devices in the M(B,S)T family.

[1] Y. Deng et al, Science 367, 895 (2020)

[2] H. Deng et al, Nature Phys. 17, 36 (2021)

[3] S. Wimmer et al, Adv. Mat. 33, 210935 (2021)