Unconventional mechanism of exchange bias in rare-earth-based kagome magnets

The kagome lattice has gained intense attention as a prototypal system for hosting a range of exotic quantum states. Within this family of kagome-based materials, RMn6Sn6 compounds (R=rare-earth element) are notable for fostering intricate interactions among band topology, electron correlation, and magnetism. Recently, exchange-bias (EB) effects were identified in kagome systems, marked by a shifted hysteresis loop after cooling the sample in an external magnetic field, suggesting its potential application in spintronics due to enhanced magnetic state stability. There is ample evidence of EB observed in bulk systems that are not limited to heterostructures, but instead host multiple coexisting magnetic phases, such as antiferromagnetic and ferromagnetic. In this work, we discover that EB arises in certain RMn6Sn6 materials possessing a perpendicular magnetic anisotropy component and a spin-glass cluster. The existence of two different switching mechanisms for each branch of the hysteresis loop gives rise to the presence of EB. In particular, we unveil the role of the spin-glass cluster in the unconventional switching process. Our work offers an in-depth understanding of new magnetic properties of kagome magnets and sets up a potential platform for designing stable magnetic devices.