Ferromagnetic-antiferromagnetic coexisting ground states and exchange bias effects in and
arXiv:2204.09420 · doi:10.1038/s41467-022-35184-7
Abstract
Natural superlattice structures ( = 1, 2,...), in which magnetic layers are separated by nonmagnetic layers, hold band topology, magnetism and reduced interlayer coupling, providing a promising platform for the realization of exotic topological quantum states. However, their magnetism in the two-dimensional limit, which is crucial for further exploration of quantum phenomena, remains elusive. Here, complex ferromagnetic (FM)-antiferromagnetic (AFM) coexisting ground states that persist up to the 2-septuple layers (SLs) limit are observed and comprehensively investigated in ( = 1) and ( = 2). The ubiquitous Mn-Bi site mixing modifies or even changes the sign of the subtle inter-SL magnetic interactions, yielding a spatially inhomogeneous interlayer coupling. Further, a tunable exchange bias effect is observed in ( = 1, 2), arising from the coupling between the FM and AFM components in the ground state. Our work highlights a new approach toward the fine-tuning of magnetism and paves the way for further study of quantum phenomena in ( = 1, 2,...) as well as their magnetic applications.
9 pages, 4 figures