Magnetic and Crystal Symmetry Control on Spin Hall Conductivity in Altermagnets

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Altermagnets are a class of materials exhibiting unique spin properties, including spin-split bands without net magnetization.
• These materials present novel opportunities for next-generation spintronic devices due to their potential for controlled spin transport.

Purpose of the Study:

• To explore the unconventional spin Hall conductivity (USHC) in representative altermagnets: RuO2, CrSb, and MnTe.
• To elucidate the influence of distinct magnetic and crystal symmetries on their spin Hall responses.
• To investigate the roles of time-reversal even and odd components in spin Hall conductivity.

Main Methods:

• Extensive first-principles calculations were employed to analyze the electronic and spin properties.
• The study examined the effects of structural tilting and magnetic axis orientation on symmetry properties.
• Material-specific analyses were performed for RuO2, CrSb, and MnTe.

Main Results:

• RuO2 shows trivial USHC under tilted geometry, indicating symmetry projections can mimic unconventional effects.
• CrSb and MnTe exhibit robust intrinsic USHC due to symmetry reduction from easy-axis magnetic ordering, without structural tilts.
• The interplay between time-reversal even and odd components was shown to be crucial for overall spin Hall conductivity.

Conclusions:

• Crystal and magnetic symmetries are key factors in modulating spin Hall responses in altermagnets.
• Tunable spin configurations in zero-net-moment materials offer promising platforms for coherent and robust spin transport.
• The findings pave the way for engineering multifunctional spintronic devices by controlling symmetry.