Abstract
Magnetization and magnetoresistance (MR) measurements are reported on superlattices consisting of alternate layers of 20 unit cell (u.c.) thick La0.7Ca0.3MnO3 (LCMO) and n u.c. LaNiO3 (LNO), where n varies from 1 to 10. The saturation field (Hs) and remnant magnetization (Mr) show antiferromagnetic (AF) interlayer coupling for n ⩽ 2 followed by an overdamped oscillatory behavior with a period of ≈ 4 u.c. with the increasing n. The low-temperature MR of the AF-coupled superlattices is characterized by a steep increase up to a critical field Hs* ( ≈ Hs) followed by a ∼ Hα (α < 1.0) dependence, whereas in the ferromagnetically coupled samples the MR rises monotonically as ∼ Hα with no Hs*. We attribute the overdamped oscillations in Mr and Hs, and the dual nature of MR to disorder modified quantum interference in the spacer layers.