Effects of spacer thickness on perpendicular anisotropy L1 0-FePt/TiN/L1 0-FePt pseudo spin valves

Abstract

Pseudo spin valves (PSVs) with the structure MgO substrate/L1 0-Fe 50Pt 50/TiN/L1 0-Fe 50Pt 50 were fabricated with varying TiN spacer thickness from 3 to 7 nm. The giant magnetoresistance (GMR) reached a maximum before diminishing with increasing TiN spacer thickness. The initial enhancement of the GMR was attributed to the reduction in interlayer coupling between the L1 0-FePt layers. However, a decline in GMR sets in when the current shunting effects negated the enhancement brought about by the improved decoupling. Magnetostatic coupling was the primary source of interlayer coupling in the PSVs. The dependence of interlayer coupling on the remanent state of the hard L1 0-FePt was also examined based on the magnitude and direction of shift in the center of the minor hysteresis loop. While magnetostatic coupling was present in fully saturated hard L1 0-FePt, dipolar stray field coupling contributed more significantly to the interlayer coupling strength in partially saturated hard L1 0-FePt. The stray field coupling strength depended on both the thickness of the spacer and the density of the reversed domains in the hard L1 0-FePt. © 2012 American Institute of Physics.