Interface induced reemergent insulator-metal transitions in ferromagnetic/antiferromagnetic manganite superlattices

Superlattices comprising of 10 layers of La0.7Ca0.3MnO3 (LCMO, thickness approximate to 8.8 nm) and Pr0.58Ca0.42MnO3 (PCMO, thickness approximate to 4.4 nm) with layer periodicity of approximate to 13.2 nm have been grown by RF magnetron sputtering on (001) oriented LaAlO3 substrates. These superlattices show strong magnetic anisotropy with the easy magnetic axis lying in the plane and hard axis along the normal to the layers. The in-situ O-2-annealed superlattices do not display any insulator-metal transition (IMT) either in current in-plane (CIP) or current perpendicular to plane (CPP) geometries. However, the ex-situ annealed superlattices show warming IMT of approximate to 220 K and another reemergent IMT at approximate to 68 K and approximate to 83 K in the CPP and "current parallel and perpendicular to plane" (CPPP) geometries. The reemergent IMTs also show thermal hysteresis, meta-resistive behaviour, and higher magnetoresistance. The interfacial electronic phase reorganization appears to be the phenomenon responsible for observed behaviour.