Giant anisotropy of Gilbert damping in a Rashba honeycomb antiferromagnet

• Giant Gilbert damping anisotropy is identified as a signature of strong Rashba spin-orbit coupling in a two-dimensional antiferromagnet on a honeycomb lattice. The phenomenon originates in spin-orbit-induced splitting of conduction electron subbands that strongly suppresses certain spin-flip processes. As a result, the spin-orbit interaction is shown to support an undamped nonequilibrium dynamical mode that corresponds to an ultrafast in-plane Neel vector precession and a constant perpendicular-to-the-plane magnetization. The phenomenon is illustrated on the basis of a two-dimensional s-d-like model. Spin-orbit torques and conductivity are also computed microscopically for this model. Unlike Gilbert damping, these quantities are shown to reveal only a weak anisotropy that is limited to the semiconductor regime corresponding to the Fermi energy staying in the close vicinity of the antiferromagnetic gap.

Subject headings

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

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