Interface-controlled antiferromagnetic tunnel junctions based on a metallic van der Waals A-type antiferromagnet

Area of Science:

• Spintronics
• Materials Science
• Condensed Matter Physics

Background:

• Magnetic tunnel junctions (MTJs) are key to spintronic devices, but limitations exist with traditional ferromagnetic materials.
• Antiferromagnetic (AFM) compounds offer potential for enhanced speed and packing density in spintronic applications.
• Exploiting AFM materials could lead to next-generation high-performance electronic devices.

Purpose of the Study:

• To report the fabrication and characterization of all-collinear antiferromagnetic tunnel junctions (AFMTJs).
• To investigate the tunneling magnetoresistance (TMR) properties of AFMTJs utilizing van der Waals AFM electrodes.
• To explore a new mechanism for TMR based on interfacial spin-polarized transport in AFM heterostructures.

Main Methods:

• Fabrication of AFMTJ heterostructures using van der Waals A-type AFM metal (Fe0.6Co0.4)5GeTe2 electrodes and WSe2 tunnel barriers.
• Measurement of tunneling magnetoresistance (TMR) ratios in response to magnetic field switching.
• Experimental and theoretical analyses to elucidate the origin of TMR, including Néel vector switching and interfacial spin-flipping.

Main Results:

• Achieved a significant tunneling magnetoresistance (TMR) ratio of up to 75% in the fabricated AFMTJ devices.
• Demonstrated that TMR arises exclusively from the antiferromagnetic state of the FCGT electrodes.
• Showcased control over TMR volatility (volatile or non-volatile) by engineering electrode layer configurations, indicating an interfacial effect.

Conclusions:

• Collinear AFMTJs fabricated with van der Waals materials exhibit performance comparable to conventional MTJs.
• A novel TMR mechanism driven by interface spin-polarized transport has been revealed, even in bulk spin-independent AFM materials.
• This work establishes a new paradigm for antiferromagnetic spintronics by harnessing AFM interface properties.