Abstract
We investigated the effects of surface modification treatment (SMT) on the perpendicular magnetic anisotropy (PMA) and the thermal tolerance of top-pinned magnetic tunnel junctions (MTJs) with a Co/Pt synthetic ferrimagnetic coupling reference layer. Applying an SMT to the bottom Pt layer increased the PMA of the overlying Co/Pt multilayer. X-ray diffraction spectrum analysis revealed that the SMT resulted in a higher crystallinity and smaller lattice spacing in the Co/Pt multilayer in the thinner bottom Pt layer, which may have increased the PMA in the Co/Pt multilayer. The tunnel magnetoresistance (TMR) ratio of the MTJ with SMT increased as the annealing temperature was increased up to 400 °C; conversely, the TMR ratio of the MTJ without SMT decreased at an annealing temperature of 400 °C. Evaluation of the m-H loops revealed that, after annealing at 400 °C, the reference layers in the MTJs after SMT possessed better magnetic properties than those in the MTJs without an SMT; this is attributable to the higher PMA of the reference layers with SMT. EDX line analysis revealed that SMT suppressed Pt diffusion to the MgO barrier, resulting in a higher thermal tolerance and larger PMA of the reference layer.
Highlights
An embedded nonvolatile memory is an essential element for future electronics as it can significantly reduce the standby power, which is an important requirement in memory applications
energy dispersive X-ray (EDX) line analysis revealed that surface modification treatment (SMT) suppressed Pt diffusion to the MgO barrier, resulting in a higher thermal tolerance and larger perpendicular magnetic anisotropy (PMA) of the reference layer
We investigated the effects of SMT on the thermal tolerance of top-pinned magnetic tunnel junctions (MTJs) with a perpendicular easy axis
Summary
An embedded nonvolatile memory is an essential element for future electronics as it can significantly reduce the standby power, which is an important requirement in memory applications. Spintronics-based memories are the most suitable for embedded nonvolatile memory applications owing to their lowvoltage and high-speed operation capabilities.. CoFeB/MgO interface magnetic tunnel junctions (MTJs) with perpendicular magnetic anisotropy (PMA) (i-pMTJs) have become the de facto standard for modern spin-transfer torque magnetic random access memory (STT-MRAM) technology because they satisfy the requirements of a low write current, high tunnel magnetoresistance (TMR) ratio, high thermal stability, and high scalability. STT-MRAM technology has a bottom-pinned structure, in which the pinned layer lies under the MgO tunneling barrier, is widely used. SOT-MRAM technology has an MTJ with a top-pinned structure, in which the pinned layer lies on the MgO tunneling barrier, has been employed because a free layer must be positioned adjacent to the channel layer
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
