Picosecond Spin Orbit Torque Switching

TL;DR

This paper demonstrates ultrafast electrical control of magnetization in a magnetic layer using 6 ps pulses, achieving reliable switching with low energy and revealing new regimes of spin torque dynamics at picosecond timescales.

Contribution

It introduces a method for deterministic magnetization switching with electrical pulses as short as 6 ps, enabling ultrafast spintronic applications and advancing understanding of spin-orbit torque dynamics.

Findings

Magnetization can be reliably switched with 6 ps electrical pulses.

Switching involves heat dissipation aiding reversal, counter to intuition.

Estimated energy cost for switching is below 1 femtojoule.

Abstract

Reducing energy dissipation while increasing speed in computation and memory is a long-standing challenge for spintronics research. In the last 20 years, femtosecond lasers have emerged as a tool to control the magnetization in specific magnetic materials at the picosecond timescale. However, the use of ultrafast optics in integrated circuits and memories would require a major paradigm shift. An ultrafast electrical control of the magnetization is far preferable for integrated systems. Here we demonstrate reliable and deterministic control of the out-of-plane magnetization of a 1 nm-thick Co layer with single 6 ps-wide electrical pulses that induce spin-orbit torques on the magnetization. We can monitor the ultrafast magnetization dynamics due to the spin-orbit torques on sub-picosecond timescales, thus far accessible only by numerical simulations. Due to the short duration of our pulses, we enter a counter-intuitive regime of switching where heat dissipation assists the reversal. Moreover, we estimate a low energy cost to switch the magnetization, projecting to below 1fJ for a (20 nm)^3 cell. These experiments prove that spintronic phenomena can be exploited on picosecond time-scales for full magnetic control and should launch a new regime of ultrafast spin torque studies and applications.