Jie Shan1
Cornell University1
The emergence of two-dimensional (2D) magnetic crystals and moiré engineering has opened the door for devising new magnetic ground states via competing interactions in moiré superlattices. In this talk, I will discuss our recent experiment on twisted bilayer CrI<sub>3</sub>, which is an A-type antiferromagnet in its natural form. We characterize the formation of large wavelength moiré pattern by TEM. We observe twist-angle-dependent magnetic ground states by magneto optical measurements. At large twist angle, CrI<sub>3</sub> bilayers are ferromagnetic (FM). Below the critical twist angle of about 3°, our result shows the coexistence of antiferromagnetic (AF) and FM domains on the moiré length scale. This arises from the stacking-dependent interlayer exchange interactions in CrI<sub>3</sub>; and it is a result of the competing interlayer AF coupling in the monoclinic stacking regions of the moiré superlattice and the energy cost for forming AF-FM domain walls. The state can further be controlled by electrostatic gating through the doping-dependent interlayer AF interaction. Our results demonstrate the possibility of engineering moiré magnetism in twisted bilayer magnetic crystals, as well as gate-voltage-controllable high-density magnetic memory storage.