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Synthetic-Ferromagnet Pinning Layers Enabling Top-Pinned Magnetic Tunnel Junctions for High-Density Embedded Magnetic Random-Access Memory KU Leuven
© 2018 American Physical Society. Magnetic tunnel junctions (MTJs) with perpendicular magnetic anisotropy (PMA) have been developed for decades for spin-transfer-torque magnetic random-access memory. Common stack designs use a hard layer (HL) with strong PMA to pin the reference layer (RL) by forming a synthetic antiferromagnet through a thin nonmagnetic coupling layer. Compared to bottom-pinned MTJs, very limited progress has been made to ...
Top-Pinned STT-MRAM Devices With High Thermal Stability Hybrid Free Layers for High-Density Memory Applications KU Leuven
© 1965-2012 IEEE. The hybrid free layer (HFL) design consisting of a single layer of CoFeB coupled via a spacer to [Co/Ni] multilayers was proposed previously to increase perpendicular magnetic anisotropy in the free layer of top-pinned magnetic tunnel junction stacks. It is thus expected that a high thermal stability factor (Δ) can be achieved in devices with small dimensions, which is required for data retention in high-density memory ...
Impact of operating temperature on the electrical and magnetic properties of the bottom-pinned perpendicular magnetic tunnel junctions KU Leuven
© 2018 Author(s). Analogous device parameters in both the parallel (P) and anti-parallel (AP) states ensure a symmetric spin-transfer-torque magnetic random-access memory operation scheme. In this study, however, we observe an increasing asymmetry in the performance metrics with operating temperature of the bottom-pinned perpendicular magnetic tunnel junction (p-MTJ) devices. A temperature-dependent increase in the contribution of the stray ...
Thermal stability analysis and modelling of advanced perpendicular magnetic tunnel junctions KU Leuven
© 2017 Author(s). STT-MRAM is a promising non-volatile memory for high speed applications. The thermal stability factor (Δ = Eb/kT) is a measure for the information retention time, and an accurate determination of the thermal stability is crucial. Recent studies show that a significant error is made using the conventional methods for Δ extraction. We investigate the origin of the low accuracy. To reduce the error down to 5%, 1000 cycles or ...
High Speed MRAM with Voltage Control of Magnetic Anisotropy (VCMA) Effect KU Leuven
Magnetic random access memory (MRAM) is gaining intensive interest for embedded and stand-alone memory applications. Its inherent non-volatility is believed to address the large stand-by energy consumption issues in the present memory hierarchy. In recent years, the spin-transfer torque (STT)-MRAM has gradually matured and started to appear in the market. Typically, STT writing of perpendicular magnetic tunnel junction (pMTJ) is limited to a few ...