Abstract
The paper presents our simulated results showing the substantial improvement of both switching speed and energy consumption in a perpendicular magnetic tunnel junction (p-MTJ), a core unit of Spin-Transfer-Torque Magnetic Random Access Memory (STT-MRAM), by the help of additional Spin-Orbit-Torque (SOT) write pulse current (WPSOT). An STT-SOT hybrid torque module for OOMMF simulation is implemented to investigate the switching behavior of a 20 nm cell in the p-MTJ. We found that the assistance of WPSOT to STT write pulse current (WPSTT) have a huge influence on the switching behavior of the free layer in the p-MTJ. For example, we could dramatically reduce the switching time (tSW) by 80% and thereby reduce the write energy over 70% as compared to those in the absence of the WPSOT. Even a very tiny amplitude of WPSOT (JSOT of the order of 102 A/m2) substantially assists to reduce the critical current density for switching of the free layer and thereby decreases the energy consumption as well. It is worth to be pointed out that the energy can be saved further by tuning the WPSOT parameters, i.e., amplitude and duration along at the threshold WPSTT. Our findings show that the proposed STT-SOT hybrid switching scheme has a great impact on the MRAM technology seeking the high speed and low energy consumption.
Highlights
Magnetic Random Access Memory (MRAM) has known to be an outstanding candidate among next-generation memories due to its various advantages, such as non-volatility, high-speed operation, high density and scalability, over other competing memories[1,2,3,4]
SOT composed of two orthogonal torques originated from the Rashba effect and the Spin-Hall effect (SHE) uses an in-plane current to reverse the state of the free layer without passing a current through the tunnel junction and separates the writing path from the reading path
Results and Discussion magnetization of the free layer, which is associated with the flowing electric currents and it may affect the magnetization dynamics of the free layer[27]
Summary
Magnetic Random Access Memory (MRAM) has known to be an outstanding candidate among next-generation memories due to its various advantages, such as non-volatility, high-speed operation, high density and scalability, over other competing memories[1,2,3,4]. Various schemes are introduced to overcome these obstacles They are the application of a manipulated write pulse current and the use of voltage control magnetic anisotropy (VCMA) or spin-orbit torque (SOT) with the assisting STT11–14. All of these schemes are gaining great attention in recent times. An STT-SOT hybrid OOMMF module uses a time evolver that integrates the LLG equation with the STT and an additional SOT term, which governs the current induced magnetization dynamics of spin-transfer a free torque (l→aτSyTeTr)26in–29th. → Heff is the effective field including the exchange, magneto-static, anisotropy and current-induced Oersted fields. α is the damping constant, MS is the saturation magnetization and tF defines the thickness of the free layer. →τSTT is the exerted torque on the magnetization of the free layer generated by the current flowing from the fixed to the free zdlaaeytsiecorrn.i→bτoeSfTdTthinceoEfnrqes.eis2lta.syOoenrf.ttHwheeoroett,eh→rσemrissh,atthnhede,uf→niτrSisOttTvoernceteporiressaSelolnontnsgcStzOheeTwd,swikreih-cilctiikhoenintootfrhqsepupienraepnsoedlnattrhwizeoastriekocniosnoadfcctfiuinerglrdeo-nnltiktgheeentomerraaqtguenede, btaiys-
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