Insulator-metal transition induced by interlayer coupling in La0.6Sr0.4MnO3/SrTiO3 superlattices -: art. no. 064429

The electronic and magnetic properties of perovskite superlattices composed of five unit-cell layers of ferromagnetic metal La0.6Sr0.4MnO3 and nonmagnetic band insulator SrTiO3 with varying layer thickness have been systematically investigated. The superlattices have well-defined periodic stacking with no sign of interlayer diffusion. The spin canting at the interfaces in La0.6Sr0.4MnO3 layers manifests itself as a suppressed magnetization and huge magnetoresistance subsisting to low temperature. The transport properties show a clear crossover from insulating to metallic perhaps by an increase in the interlayer electron hopping through SrTiO3 layers when the SrTiO3 layer thickness is reduced. This crossover is also discerned in the infrared optical spectra as the filling of absorption in the low-energy region.