Growth and magnetoresistive properties of (LaMnO3)(m)(SrMnO3)(n) superlattices

Artificial (LaMnO3)(m)(SrMnO3)(n) superlattices, n/(m+n)=0.26, were grown w ith pulsed-laser deposition, and the superlattice period Lambda was varied. Their structural characteristics were investigated using x-ray diffraction and electron microscopy. When Lambda < a(p) (perovskite lattice parameter) , bulk-like properties of La0.74Sr0.26MnO3 are obtained: T-MI (metal-to-ins ulator transition temperature) approximate to T-c (Curie temperature) appro ximate to 345 K and -MR (magnetoresistance) approximate to 100%. Increasing Lambda (to 21 a(p)) leads to a decrease in the T-c, the low-temperature ma gnetization, the magnetoresistance, and the T-MI-eventually becoming insula ting at low temperatures. These effects can be explained by Mn3+/Mn4+ separ ation arising from the artificially induced La/Sr order. (C) 1999 American Institute of Physics. [S0003- 6951(99)04843-3].