Ultrafast Magnetization Reversal by Picosecond Electrical Pulses

TL;DR

This paper demonstrates that picosecond electrical pulses can deterministically reverse magnetization in magnetic materials within 10 picoseconds, offering a faster and energy-efficient method for magnetic switching compared to existing techniques.

Contribution

It introduces a novel electrically driven magnetization reversal mechanism using ultrafast electron excitation, significantly faster than traditional spin-transfer or spin-orbit torque methods.

Findings

Magnetization reverses in approximately 10 ps.

Switching energy density is about 4 fJ per (20 nm)^3 cell.

The process is more than ten times faster than previous electrical switching methods.

Abstract

The field of spintronics involves the study of both spin and charge transport in solid state devices with a view toward increasing their functionality and efficiency. Alternatively, the field of ultrafast magnetism focuses on the use of femtosecond laser pulses to excite electrons in magnetic materials, which allows the magnetic order to be dramatically changed on unprecedented sub-picosecond time-scales. Here, we unite these two distinct research activities by using picosecond electrical pulses to rapidly excite electrons in a magnetic metal. We are able to deterministically and repetitively reverse the magnetization of a GdFeCo film with sub-10 picosecond electrical pulses. The magnetization reverses in ~10ps, which is more than an order of magnitude faster than any other electrically controlled magnetic switching. We attribute the deterministic switching of the magnetization to ultrafast excitation of the electrons, a fundamentally different mechanism from other current driven switching mechanisms such as spin-transfer-torque (STT) or spin-orbit-torque (SOT). The energy density required for switching is measured and the process is found to be efficient, projecting to only 4 fJ needed to switch a (20 nm)^3 cell, which is comparable to other state-of-the-art STT-MRAM memory devices. This discovery will launch a new field of research into picosecond spintronic phenomena and devices.