Magnon Polarons induced by a magnetic field gradient

Abstract

In this work, we report the theoretical possibility of generating magnon polaron excitations through a space-varying magnetic field. The spatial dependence of the magnetic field in the Zeeman interaction gives rise to a magnon-phonon coupling when a magnetic field gradient is applied, and such a coupling depends directly on the strength of the gradient. It is also predicted that the direction of the magnetic field gradient allows control over which phonon polarization couples to the magnons in the material. Here we develop the calculations of the magnon-phonon coupling for an arbitrary (anti)ferromagnet, which are later used to numerically study its consequences. These results are compared to the ones obtained with the phenomenological magnetoelastic coupling in YIG, where we show that the magnon polaron bandgap seen in YIG can be also obtained with a magnetic field gradient of $\sim 0.1$T/m which can be achieved with the current experimental techniques. Our results propose a new way of controlling the magnetoelastic coupling in an arbitrary material and open a new route to exploit the magnon-phonon interaction in magnonic and spintronic devices.

References in corpus (10)

• Magnon Polarons in the Spin Seebeck Effect
• Topological Magnons and Edge States in Antiferromagnetic Skyrmion Crystals
• Magnon-phonon interactions in magnetic insulators
• Coherent elastic excitation of spin waves
• Individual addressing of trapped ions and coupling of motional and spin states using rf radiation
• Nonlocal magnon-polaron transport in yttrium iron garnet
• Broadband magnetoelastic coupling in magphonic crystals for high-frequency nanoscale spin wave generation
• Magnon polarons in the spin Peltier effect
• Magnon-polarons in cubic collinear Antiferromagnets
• Magnon-polaron excitations in the noncollinear antiferromagnet Mn${}_3$Ge