Magnetotransport of manganite superlattices: Investigating the role of a magnetic insulating spacer

Magnetotransport data are presented for a set of manganite superlattices comprising La_2/3 Sr_1/3 MnO₃ as the ferromagnetic (FM) metallic layers (thickness 11.9 nm) and Pr_2/3 Ca_1/3 MnO₃ as the antiferromagnetic insulating spacer (IS) with thicknesses t_IS between 0.8 and 7.6 nm. Previous studies on this system showed the presence of FM inclusions within the IS, with a notable magnetization peak at t_IS ∼3 nm. Now, we show that this peak is also accompanied by a maximum in the magnetoresistance (MR). Moreover, the MR data of all the samples scale in a single curve, MR∝ M_IS ², where MIS is the magnetization of the IS. These results provide a quantitative demonstration of the feasibility to improve the response of engineered MR devices by including magnetically active IS instead of the usual nonmagnetic compounds.