Wang Yu-Xuan, Graham Thomas K M, Rama-Eiroa Ricardo, Islam Md Ariful, Badarneh Mohammad H, Nunes Gontijo Rafael, Tiwari Ganesh Prasad, Adhikari Tibendra, Zhang Xin-Yue, Watanabe Kenji, Taniguchi Takashi, Besson Claire, J G Santos Elton, Lin Zhong, Zhou Brian B
Department of Physics, Boston College, Chestnut Hill, MA, USA.
Donostia International Physics Center (DIPC), Donostia-San Sebastián, Spain.
Nat Mater. 2025 Jun 12. doi: 10.1038/s41563-025-02259-x.
Interfacial exchange coupling between antiferromagnets (AFMs) and ferromagnets (FMs) crucially makes it possible to shift the FM hysteresis, known as exchange bias, and to switch AFM states. Two-dimensional magnets unlock opportunities to combine AFM and FM materials; however, the buried AFM-FM interfaces obtained by stacking remains challenging to understand. Here we demonstrate interfacial control via intralayer exchange coupling in the layered AFM CrPS, where connected even and odd layers realize pristine lateral interfaces between AFM-like and FM-like regions. We distinguish antiphase even-layer states by scanning nitrogen-vacancy centre magnetometry due to a weak surface magnetization. This surface magnetization enables control over the even-layer state, with different regions switching at distinct fields due to their own lateral couplings. We toggle three AFM domains adjacent to a FM-like region and demonstrate a tunable multilevel exchange bias. Our nanoscale visualization unveils the microscopic origins of exchange bias and advances single two-dimensional crystals for hybrid AFM-FM technologies.
反铁磁体（AFM）与铁磁体（FM）之间的界面交换耦合对于实现铁磁体磁滞的移动（即交换偏置）以及切换反铁磁体状态至关重要。二维磁体为结合反铁磁体和铁磁体材料提供了机会；然而，通过堆叠获得的埋入式反铁磁体 - 铁磁体界面仍难以理解。在此，我们展示了通过层内交换耦合在层状反铁磁体CrPS中实现的界面控制，其中相连的偶数层和奇数层在类反铁磁体区域和类铁磁体区域之间实现了原始的横向界面。由于表面磁化较弱，我们通过扫描氮空位中心磁力测量法区分反相偶数层状态。这种表面磁化能够控制偶数层状态，由于不同区域自身的横向耦合，它们在不同磁场下切换。我们切换了与类铁磁体区域相邻的三个反铁磁体畴，并展示了可调谐的多级交换偏置。我们的纳米级可视化揭示了交换偏置的微观起源，并推动了用于混合反铁磁体 - 铁磁体技术的单个二维晶体的发展。
