A Perspective on Electrical Generation of Spin Current for Magnetic Random Access Memories
| Autor: | Safranski, Christopher, Sun, Jonathan Z., Kent, Andrew D. |
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| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Applied Physics Letters 120, 160502 (2022) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1063/5.0084551 |
| Popis: | Spin currents are used to write information in magnetic random access memory (MRAM) devices by switching the magnetization direction of one of the ferromagnetic electrodes of a magnetic tunnel junction (MTJ) nanopillar. Different physical mechanisms of conversion of charge current to spin current can be used in 2-terminal and 3-terminal device geometries. In 2-terminal devices, charge-to-spin conversion occurs by spin filtering in the MTJ's ferromagnetic electrodes and present day MRAM devices operate near the theoretically expected maximum charge-to-spin conversion efficiency. In 3-terminal devices, spin-orbit interactions in a channel material can also be used to generate large spin currents. In this perspective article, we discuss charge-to-spin conversion processes that can satisfy the requirements of MRAM technology. We emphasize the need to develop channel materials with larger charge-to-spin conversion efficiency -- that can equal or exceed that produced by spin filtering -- and spin currents with a spin polarization component perpendicular to the channel interface. This would enable high-performance devices based on sub-20 nm diameter perpendicularly magnetized MTJ nanopillars without need of a symmetry breaking field. We also discuss MRAM characteristics essential for CMOS integration. Finally, we identify critical research needs for charge-to-spin conversion measurements and metrics that can be used to optimize device channel materials and interface properties prior to full MTJ nanopillar device fabrication and characterization. Comment: 12 pages, 3 figures, 1 table |
| Databáze: | arXiv |
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