Two-dimensional spinodal interface in one-step grown graphene-molybdenum carbide heterostructures

Heterostructures made by stacking different materials on top of each other are expected to exhibit unusual properties and new phenomena. Interface of the heterostructures plays a vital role in determining their properties. Here, we report the observation of a two-dimensional (2D) spinodal interface in graphene-molybdenum carbide ({\alpha}-Mo2C) heterostructures, which arises from spinodal decomposition occurring at the heterointerface, by using scanning tunneling microscopy. Our experiment demonstrates that the 2D spinodal interface modulates graphene into whispering gallery resonant networks filled with quasi-bound states of massless Dirac fermions. Moreover, below the superconducting transition temperature of the underlying {\alpha}-Mo2C, the 2D spinodal interface behaves as disorders, resulting in the breakdown of the proximity-induced superconductivity in graphene. Our result sheds new light on tuning properties of heterostructures based on interface engineering.