Tuning the metal-insulator transitions of (SrMnO3)n/(LaMnO3)2n superlattices: The role of interfaces

The temperature dependence of the transport properties of (SrMnO3)n/(LaMnO3)2n superlattices has been systematically investigated by changing the number of interfaces while keeping the total thickness of the system fixed. The superlattices undergo a rich variety of transitions among metal, Mott variable range hopping insulator, interaction-induced Efros-Shklovskii insulator, and polaronic insulator. Interfaces play a fundamental role in tuning the metal-insulator transitions controlling the effective doping of the different layers. In the case of a bilayer, as clarified by a theoretical model, the single interface can extend its effects well far from it in the bulk layer.