Electrically Tunable Picosecond-Scale Octupole Fluctuations in Chiral Antiferromagnets

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Octupole order parameters in nanoscale chiral antiferromagnets (AFMs) are crucial for advanced spintronic applications.
• Understanding their relaxation dynamics is key to device design and performance.

Purpose of the Study:

• To present a theoretical framework for the relaxation time of octupole order parameters in chiral AFMs.
• To investigate relaxation mechanisms and timescales under thermal baths and spin injection.
• To propose methods for electrically tuning octupole relaxation.

Main Methods:

• Stochastic spin dynamics simulations were employed to model octupole moment relaxation.
• Langer's theory was combined with an effective low-energy description of octupole dynamics.
• Analogies with XY magnets and Josephson junctions were used to explore electrical tuning.

Main Results:

• Identified two distinct relaxation mechanisms: barrier escape and precessional dephasing.
• Demonstrated picosecond-timescale relaxation, orders of magnitude faster than dipolar order parameters.
• Derived analytical expressions for relaxation times, showing parallels with XY magnet dipole relaxation.

Conclusions:

• The study provides fundamental insights into octupole relaxation dynamics in chiral AFMs.
• Exchange fields play a role analogous to dipole fields in relaxation processes.
• A novel scheme for electrical tuning of octupole relaxation times was proposed, paving the way for next-generation spintronic devices.