Current-induced magnetization switching in CoTb amorphous single layer

TL;DR

This study demonstrates efficient spin-orbit torque switching in amorphous CoTb single-layer films with perpendicular magnetic anisotropy, showing potential for energy-efficient memory devices without heavy metal interfaces.

Contribution

It reveals that amorphous CoTb films can be switched via SOT without interfacial Dzyaloshinskii-Moriya interaction, highlighting a new mechanism involving spin Hall effects from Co and Tb.

Findings

Switching persists in films thicker than 10 nm.

Low assist field (~20 Oe) enables full switching.

SOT effective field changes sign with Tb concentration.

Abstract

We demonstrate spin-orbit torque (SOT) switching of amorphous CoTb single layer films with perpendicular magnetic anisotropy (PMA). The switching sustains even the film thickness is above 10 nm, where the critical switching current density keeps almost constant. Without the need of overcoming the strong interfacial Dzyaloshinskii-Moriya interaction caused by the heavy metal, a quite low assistant field of ~20 Oe is sufficient to realize the fully switching. The SOT effective field decreases and undergoes a sign change with the decrease of the Tb-concentration, implying that a combination of the spin Hall effect from both Co and Tb as well as an asymmetric spin current absorption accounts for the SOT switching mechanism. Our findings would advance the use of magnetic materials with bulk PMA for energy-efficient and thermal-stable non-volatile memories, and add a different dimension for understanding the ordering and asymmetry in amorphous thin films.