Ab initio mismatched interface theory of graphene on α-RuCl₃: doping and magnetism

The possibilities for creating van der Waals heterostructures are limitless with the rich palette including Mott insulating α-RuCl₃ and semi-metallic graphene. However, the study of such "mismatched interfaces'' calls for an innovative way of capturing the underlying physics of these complex systems, that goes beyond standard ab initio methods. We propose a general strategy for studying such interfaces, "mismatched interface theory," and apply it to a α-RuCl₃-graphene heterostructure in which there is significant lattice mismatch between the two crystals. Our results indicate charge transfer from graphene to the Ru layer in α-RuCl₃ directly proportional to the number of carbon atoms present in the system, corresponding to uniform doping of 4.7% in the α-RuCl₃-graphene heterostructure. We further demonstrate that this doping may be tuned by applying uniaxial pressure to the heterostructure, and investigate the effects of the doping on the zigzag- and ferromagnetic-ordered low-energy stable states of α-RuCl₃ which lie close to the antiferromagnetic Kitaev spin liquid.