Fast, low-current spin-orbit torque switching of magnetic tunnel junctions through atomic modifications of the free layer interfaces

TL;DR

This paper presents a novel interface modification technique using Hf layers in magnetic tunnel junctions that significantly reduces switching current and enables fast, reliable spin-orbit torque switching at room temperature.

Contribution

Introducing atomic-scale Hf modifications at interfaces to enhance magnetic anisotropy and reduce spin loss, leading to lower switching currents and faster operation in MTJs.

Findings

Switching current density of 5.4 x 10^6 A/cm^2 achieved

Switching with 2 ns current pulses demonstrated

Over threefold reduction in switching current compared to previous devices

Abstract

Future applications of spin-orbit torque will require new mechanisms to improve the efficiency for switching nanoscale magnetic tunnel junctions (MTJs), while also controlling the magnetic dynamics to achieve fast, nanosecond scale performance with low write error rates. Here we demonstrate a strategy to simultaneously enhance the interfacial magnetic anisotropy energy and suppress interfacial spin memory loss by introducing sub-atomic and monatomic layers of Hf at the top and bottom interfaces of the ferromagnetic free layer of an in-plane magnetized three-terminal MTJ device. When combined with a beta-W spin Hall channel that generates spin-orbit torque, the cumulative effect is a switching current density of 5.4 x 106 A/cm2, more than a factor of 3 lower than demonstrated in any other spin-orbit-torque magnetic memory device at room temperature, and highly reliable switching with current pulses only 2 ns long.