Néel Spin-Orbit Torque Driven Antiferromagnetic Resonance in Mn_{2}Au Probed by Time-Domain THz Spectroscopy

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Néel spin-orbit torques (NSOTs) are a recently discovered phenomenon in metallic antiferromagnets.
• Antiferromagnetic materials offer potential for high-speed data storage due to their fast dynamics.

Purpose of the Study:

• To investigate the excitation of collective modes in the terahertz (THz) range.
• To explore the role of NSOTs in driving these modes in Mn2Au.
• To assess the potential of Mn2Au for ultrafast memory applications.

Main Methods:

• Utilized temperature-dependent THz spectroscopy to probe collective modes.
• Analyzed absorption spectra and mode frequencies.
• Employed theoretical modeling to understand the driving mechanism.

Main Results:

• Observed a strong THz absorption mode near 1 THz, identified as an in-plane antiferromagnetic resonance (AFMR).
• The AFMR mode softened and decreased in intensity with increasing temperature (4–450 K).
• AFMR absorption strength in Mn2Au significantly exceeded that in antiferromagnetic insulators.

Conclusions:

• Inferred that current-induced NSOTs are the primary mechanism driving the observed AFMR.
• The electric field component of THz pulses drives AC currents, which in turn excite the AFMR.
• Mn2Au is a promising material for developing antiferromagnetic ultrafast memory devices due to electric manipulation of the Néel order parameter.