GMR multilayers on a new embossed surface

It has been shown that the deposition of magnetoresistive multilayers on stepped, corrugated or V-grooved surfaces can increase the magnitude of giant magnetoresistance (GMR). The primary reason for this enhancement of GMR is that the in-the-substrate-plane current crosses multiple magnetic layers which results in the mixed current-in-plane and current perpendicular to plane modes called current at an angle to the plane mode. In our studies, we use a novel substrate consisting of nano-hemispheres organized in a regular hexagonal array. The substrate was produced by anodization of Al and subsequent etching of alumina membrane. Scanning electron microscopy was used to investigate larger areas and cross-sectional images of the embossed surface, whereas detailed analysis of the surface structure was made by high resolution atomic force microscopy. We deposited uncoupled Co/Cu multilayers on the alumina substrate with an 8-nm-thick Fe buffer using magnetron sputtering. Our preliminary studies of the magnetotransport using a physical property measurement system (quantum design) demonstrated that the samples on the new substrate have an enhanced GMR effect compared to the samples with similar composition deposited on smooth (100) Si wafers. Because of the inexpensive method of fabrication of the embossed substrate, the GMR structures deposited on this substrate have a potential for use in magnetic sensors.