Picosecond Spin-Orbit Torque Induced Coherent Magnetization Switching in a Ferromagnet
| Autor: | Polley, Debanjan, Pattabi, Akshay, Rastogi, Ashwin, Jhuria, Kaushalya, Diaz, Eva, Singh, Hanuman, Lemaitre, Aristide, Hehn, Michel, Gorchon, Jon, Bokor, Jeffrey |
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| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Science Advances 9, edah5562 (2023) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1126/sciadv.adh5562 |
| Popis: | Electrically controllable non-volatile magnetic memories show great potential for the replacement of semiconductor-based technologies. Recently there has been strong interest in spin-orbit torque (SOT) induced magnetization reversal due to the device's increased lifetime and speed of operation. However, recent SOT switching studies reveal an incubation delay in the ~ns range due to stochasticity in the nucleation of a magnetic domain during reversal. Here, we experimentally demonstrate ultrafast SOT-induced magnetization switching dynamics of a ferromagnet with no incubation delay by avoiding the nucleation process and driving the magnetization coherently. We employ an ultrafast photo-conducting switch and a co-planar strip line to generate and guide ~ps current pulses into the heavy metal/ferromagnet layer stack and induce ultrafast SOT. We use magneto-optical probing to investigate the magnetization switching dynamics with sub-picosecond time resolution. Depending on the relative current pulse and in-plane magnetic field polarities, we observe either an ultrafast demagnetization and subsequent recovery along with a SOT-induced precessional oscillation, or ultrafast SOT switching. The magnetization zero-crossing occurs in ~70 ps, which is approximately an order of magnitude faster than previous studies. Complete switching needs ~250 ps and is limited by the heat diffusion to the substrate. We use a macro-magnetic simulation coupled with an ultrafast heating model to analyze the effect of ultrafast thermal anisotropy torque and current-induced torque in the observed dynamics. Good agreement between our experimental results and the macro-spin model shows that the switching dynamics are coherent and present no noticeable incubation delay. Our work suggests a potential pathway toward dramatically increasing the writing speed of SOT magnetic random-access memory devices. Comment: 17 pages, 4 figures, Supplemental Material |
| Databáze: | arXiv |
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