Perovskite oxide tricolor superlattices with artificially broken inversion symmetry by interface effects

We have designed and fabricated spin superlattices composed of three kinds of perovskite oxides: ferromagnetic La0.6Sr0.4MnO3 (LSMO) sandwiched by two nonmagnetic insulators, SrTiO3 (STO), and LaAlO3 (LAO). Conventional superlattices, structured as alternating stack of two components, preserve centrosymmetry. By stacking three compounds repeatedly in an asymmetric sequence such as (LAO/LSMO/STO)(n), one can break the inversion symmetry. Magnetic and transport properties of the superlattices clearly indicate that the STO and LAO layers modulate the ferromagnetic spin order in LSMO layers adjacent to the interfaces in a different manner, giving rise to broken inversion symmetry of magnetic structure in the (LAO/LSMO/STO)(n) superlattices. (C) 2002 American Institute of Physics.