Fig. 4: Exchange bias effects of the FM component in MnBi₄Te₇ and MnBi₆Te₁₀ samples.

a, b Exchange bias effects of the FM component in the 6-SL MnBi₄Te₇ (a) and 6-SL MnBi₆Te₁₀ (b) measured at 4 K. The direction of the exchange bias can be tuned by the historical polarization field (blue for positive polarization field and orange for negative polarization field). The exchange bias effect observed in MnBi₆Te₁₀ is opposite to that of MnBi₄Te₇. Colored dashed lines represent H_E. c, d Temperature-dependent exchange bias effects of MnBi₄Te₇ and MnBi₆Te₁₀ after initialized by positive polarization field, with the full hysteresis loops being presented as the references (gray lines). The red and green arrows represent the H_c– and H_c+ for the biased hysteresis loop, respectively, and the blue dashed lines represent H_E. e, f Evolution of H_c and H_E with temperature in MnBi₄Te₇ (blue squares) and MnBi₆Te₁₀ (green squares).