Spin-Splitting Magnetoresistance in Altermagnetic RuO₂ Thin Films

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Altermagnets exhibit unique correlations between magnetic exchange and crystal structure, offering spintronic potential.
• The altermagnetism of Ruthenium Dioxide (RuO2) remains debated despite its early discovery.

Purpose of the Study:

• To resolve the controversy surrounding RuO2 altermagnetism.
• To demonstrate a novel spin-splitting magnetoresistance (SSMR) effect driven by nonrelativistic spin splitting.
• To establish an electric method for probing the Néel vector in altermagnets.

Main Methods:

• Investigated magnetoresistance in (101)-RuO2/Co bilayers.
• Analyzed the spin-splitting magnetoresistance (SSMR) effect.
• Characterized the angular and temperature dependence of the SSMR effect.

Main Results:

• A sizable spin-splitting magnetoresistance (SSMR) effect was observed and disentangled.
• The SSMR effect exhibited unusual angular dependence with a phase shift, linked to Néel vector orientation.
• Pronounced temperature dependence of SSMR was observed, correlating with electron scattering.
• A Néel vector orientation along the [001] direction in RuO2 was unveiled.

Conclusions:

• The study demonstrates that spin-splitting magnetoresistance (SSMR) is a viable method for probing altermagnet Néel vectors.
• Long-range magnetic order is confirmed in thin films of RuO2.
• The findings contribute to understanding and utilizing altermagnetic materials in spintronics.