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

Magnetotransport data are presented for a set of manganite superlattices comprising La2/3Sr1/3MnO3 as the ferromagnetic (FM) metallic layers (thickness 11.9 nm) and Pr2/3Ca1/3MnO3 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) similar to 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 proportional to M-IS(2), where M-IS 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. (C) 2008 American Institute of Physics.