Lattice-driven femtosecond magnon dynamics in $\alpha$-MnTe

Abstract

The light-induced femtosecond dynamics of the sublattice magnetizations in the antiferromagnetically ordered phase of the semiconductor $\alpha$-MnTe is investigated theoretically as function of an external driving field. The electromagnetic field is coupled to optical modes and the concomitant atomic displacements modulate the Heisenberg exchange couplings. We derive the equations of motion for the time-dependent sublattice magnetization in spin wave theory and analyze the contributions from the driven magnon modes. The antiferromagnetic order parameter exhibits coherent longitudinal oscillations determined by the external driving frequency which decay due to dephasing. Including a phenomenological dissipative term to mimic spin-lattice relaxation processes leads to relaxation back to thermal equilibrium. We provide approximate analytic solutions of the resulting differential equations which allow us to understand the effect of the driving light pulse on the amplitude, frequency, and lifetime of the coherent spin dynamics.

arXiv comment20 pages, 15 figures

References in corpus (9)

• Antiferromagnetic opto-spintronics: Part of a collection of reviews on antiferromagnetic spintronics
• An effective magnetic field from optically driven phonons
• Ultrafast photo-magnetic recording in transparent medium
• Multiple-stable anisotropic magnetoresistance memory in antiferromagnetic MnTe
• Macrospin Dynamics in Antiferromagnets Triggered by Sub-20 femtosecond Injection of Nanomagnons
• Frequency and wavenumber selective excitation of spin waves through coherent energy transfer from elastic waves
• Topological magnetic excitations
• Femtosecond phononic coupling to both spins and charges in a room temperature antiferromagnetic semiconductor
• Dynamical properties of a driven dissipative dimerized $S=1/2$ chain