Two-Dimensional Superconductivity at the Titanium Sesquioxide Heterointerface.

The study of exotic superconductivity in two dimensions has been a central theme in the solid state and materials research communities. Experimentally exploring and identifying exotic, fascinating interface superconductors with a high transition temperature (Tc) are challenging. Here, we report an experimental observation of intriguing two-dimensional superconductivity with a Tc of up to 3.8 K at the interface between a Mott insulator Ti2O3 and polar semiconductor GaN. At the verge of superconductivity, we also observe a striking quantum metallic-like state, demonstrating that it is a precursor to the two-dimensional superconductivity as the temperature is decreased. Our work shows an exciting opportunity to exploit the underlying, emergent quantum phenomena at the heterointerfaces via heterostructure engineering.