Unconventional Spin-Orbit Torques by 2D Multilayered MXenes for Future Nonvolatile Magnetic Memories

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• MXenes are 2D materials with diverse functionalities attracting significant research interest.
• Exploring new applications for MXenes in electronic devices, particularly magnetic memory, is crucial.

Purpose of the Study:

• To develop a novel spin-orbit torque (SOT) bilayer structure utilizing MXene (Cr2N) for potential use in ultrahigh-integrated magnetic memory.
• To investigate the mechanisms behind field-free current-induced magnetization switching in this new material system.

Main Methods:

• Fabrication of a substrate//Cr2N/[Co/Pt]3/MgO bilayer structure using magnetron sputtering.
• Experimental demonstration of field-free current-induced magnetization switching.
• First-principles calculations to predict electronic properties.
• X-ray magnetic circular dichroism (XMCD) to probe interfacial magnetic moments.

Main Results:

• Demonstrated field-free current-induced magnetization switching in the Cr2N/ [Co/Pt]3 heterostructure, independent of current direction relative to Cr2N crystal symmetry.
• Observed increasing SOT efficiency with Cr2N thickness.
• First-principles calculations predicted a dominant out-of-plane orbital-Hall conductivity in Cr2N.
• XMCD revealed an induced out-of-plane magnetic moment of Cr at the Cr2N/Co interface.

Conclusions:

• The study highlights the potential of 2D MXene materials for advanced spintronic devices.
• Unconventional out-of-plane SOT is attributed to the intrinsic orbital-Hall effect in bulk Cr2N and interfacial effects like spin-filtering.