  In this paper, the perpendicular magnetic anisotropy (PMA) is tailored by
changing the thickness of the free layer with the objective of producing MTJ
nano-pillars with smooth linear resistance dependence with both in-plane
magnetic field and DC bias. We furthermore demonstrate how this linear bias
dependence can be used to create a zero-threshold broadband voltage rectifier,
a feature which is important for rectification in wireless charging and energy
harvesting applications. By carefully balancing the amount of PMA acting in the
free layer the measured RF to DC voltage conversion efficiency can be made as
large as 11%.
