Magnetic tunnel junction made of abundant materials for memory and dynamic applications

Abstract

Abstract Magnetic tunnel junction (MTJ) used currently for data storage are characterized by perpendicular magnetic anisotropy, which is beneficial in terms of low current density required for switching and the thermal stability of the free magnetic layer. The other ferromagnet of MTJ, namely the reference layer is fixed using so-called synthetic antiferromagnetic (SAF) structure, which typically involves less-abundant material, such as Pt or Pd. We present an alternative stack structure, with the SAF based on Ni-Co superlattices, which is Pt-free. The reference layer of MTJ is characterized by the switching field above 250 mT. In MTJ nanopillars of diameter down to 80 nm, we show a robust switching with voltage pulses between 1 ms and 5 ns, tunneling magnetoresistance up to 140%, high thermal stability and switching current density of 2.6 MA/cm2. Our result show a promising route towards design of MTJs made of abundant materials.