Coherent THz Spin Dynamics in Antiferromagnets Beyond the Approximation of the Néel vector

Abstract

Controlled generation of coherent spin waves with highest possible frequencies and the shortest possible wavelengths is a cornerstone of spintronics and magnonics. Here, using the Heisenberg antiferromagnet RbMF${}_3$, we demonstrate that laser-induced THz spin dynamics corresponding to pairs of mutually coherent counter propagating spin waves with the wavevectors up to the edge of the Brillouin zone cannot be understood in terms of magnetization and antiferromagnetic (Néel) vectors, conventionally used to describe spin waves. Instead, we propose to model such spin dynamics using the spin correlation function. We derive a quantum-mechanical equation of motion for the latter and emphasize that, unlike the magnetization and antiferromagnetic vectors the spin correlations in antiferromagnets do not exhibit inertia.

Main article contains 7 pages, 3 figures. With Supplementary material

References in corpus (2)

• Selection rules for ultrafast laser excitation and detection of spin correlations dynamics in a cubic antiferromagnet
• Parametrically driven THz magnon-pairs: predictions towards ultimately fast and minimally dissipative switching

Cited by in corpus (5)

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• Nonclassical dynamics of Néel vector and magnetization accompanied by THz and high-harmonic radiation from ultrafast-light-driven NiO antiferromagnet insulator
• Role of magnon-magnon interaction in optical excitation of coherent two-magnon modes
• Time-dependent Schwinger boson mean-field theory of supermagnonic propagation in 2D antiferromagnets