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Seminar: 'Progress towards picosecond on-chip magnetic memory' (Lecture)

Tuesday 3 May 2022Add to my calendar
from 16:00
Prof. Jeffrey Bokor (Department of Electrical Engineering and Computer Sciences, University of California, USA)

This talk will summarize the prospects of ultrafast spintronics and opto-magnetism as a pathway to high-performance, energy-efficient, nonvolatile embedded memory in digital integrated circuit applications. Conventional spintronic devices, such as spin-transfer-torque magnetic-resistive random-access memory (STT-MRAM) and spin-orbit torque MRAM (SOT-MRAM), are promising due to their non-volatility, energy-efficiency, and high endurance. STT-MRAMs are now entering into the commercial market, however they are limited in write speed to the nanosecond timescale. Improvement in the write speed of spintronic devices can significantly increase their usefulness as viable alternatives to the existing CMOS-based devices. Here we discuss recent studies which advance the field of ultrafast spintronics. An optimized ferromagnet-ferrimagnet exchange-coupled magnetic stack, which can serve as the free layer of a magnetic tunnel junction (MTJ), can be optically switched as fast as ~3 ps.  Integration of ultrafast magnetic switching of such a stack into an MTJ device has enabled electrical readout of the switched state with relatively large tunneling magnetoresistance ratio. Purely electronic ultrafast spin-orbit torque induced switching of a ferromagnet has been demonstrated using ~6 ps long charge current pulses, offering a pathway to full all-electronic, on-chip integration (no laser involved). We will conclude by discussing some of the challenges that remain to be addressed to accelerate ultrafast spintronics technologies toward practical implementation in high-performance digital information processing systems.