Quantum Hall effect in a monolayer graphene magnetized by an antiferromagnet*

We experimentally demonstrate the quantum Hall effect in a monolayer graphene magnetized by an underlying layer of an antiferromagnet. When interfacing with the AFM, the π bond formed by the p orbitals of carbon is found to sufficiently overlap with the Cr atoms in the AFM layer, and therefore experiences a sizeable Hund's-rule exchange energy. Through field-cooling, the change in the antiferromagnetic order modifies the spin splitting, and thereby shifts quantum Hall plateau, as well as the SdH oscillation. This transport behavior is then used to quantitatively estimate the spin split energy ( about several hundreds of meV ).