Probing magnetic ordered states in thin crystals of spin-orbit assisted Mott insulators using a graphene heterostructure*

Spin-orbit driven Mott insulators such as sodium Iridate (Na₂IrO₃) and alpha-ruthenium chloride (α-RuCl₃) present exciting properties thanks to a combination of electronic correlations, spin-orbit coupling, crystal field effects and a honeycomb arrangement of the Ir and Ru ions respectively. These materials are in close proximity to a Kitaev-Heisenberg system, yielding exciting ground states such as gapless spin liquids and a variety of ordered states. The insulating character Na₂IrO₃ and RuCl₃ has limited experimental probes to those that don’t require charge transport, such as thermal Hall conductance, magnetic susceptibility or neutron scattering, with few works using electronic transport. Here, we present signature of magnetic ordered states in these materials through a van der Waals heterostructure that exploits the conducting character of graphene.