Unidirectional Spin Hall Magnetoresistance in Antiferromagnetic Heterostructures.

Area of Science:

• Condensed Matter Physics
• Spintronics
• Materials Science

Background:

• Unidirectional spin Hall magnetoresistance (USMR) is a phenomenon typically observed in heavy metal/ferromagnet bilayers.
• Antiferromagnetic (AFM) materials offer potential for novel spintronic devices due to their unique magnetic properties.

Purpose of the Study:

• To investigate the presence and origin of USMR in a system involving an antiferromagnetic insulator.
• To explore the theoretical underpinnings of USMR in antiferromagnetic systems and compare it to ferromagnetic systems.

Main Methods:

• Experimental measurements of USMR in platinum/alpha-iron oxide (Pt/α-Fe_{2}O_{3}) bilayers under varying magnetic fields and temperatures.
• Theoretical modeling to understand the role of antiferromagnetic magnons and spin orbit torque.

Main Results:

• USMR was successfully observed in Pt/α-Fe_{2}O_{3} bilayers, demonstrating its occurrence in antiferromagnetic insulators.
• The study confirmed the magnonic origin of the observed USMR, attributing it to the imbalance of antiferromagnetic magnon creation and annihilation.
• Theoretical analysis revealed that the USMR in this system is governed by the antiferromagnetic magnon number and exhibits non-monotonic field dependence.

Conclusions:

• The findings extend the generality of USMR to antiferromagnetic insulator systems.
• This research paves the way for highly sensitive detection of antiferromagnetic spin states, crucial for future spintronic applications.