Direct imaging of delayed magneto dynamic modes induced by surface acoustic waves*

Changes in strain can be used to modify electronic and magnetic properties in crystal structures, to manipulate nanoparticles and cells, or to control chemical reactions. The magneto-elastic effect--the change of magnetic properties caused by the elastic deformation (strain) of a magnetic material--has been proposed as an alternative approach to magnetic fields for the low-power control of magnetization states of nanoelements since it avoids charge currents, which entail ohmic losses. Multiferroic heterostructures and nanocomposites have exploited this effect in search of electric control of magnetic states, mostly in static regimes. We have studied the effect of dynamic strain accompanying a surface acoustic wave on magnetic nanostructures in thermal equilibrium. We have developed a new experimental technique based on stroboscopic X-ray microscopy that provides a pathway to the quantitative study of strain waves and magnetization at the nanoscale. We have simultaneously imaged the temporal evolution of both strain waves and magnetization dynamics of nanostructures at the picosecond timescale and found that magnetization modes have a delayed response to the strain modes, adjustable by the magnetic domain configuration. The results I will present in this talk provide fundamental insight into magnetoelastic coupling in nanostructures having implications in the design of strain-controlled magnetostrictivenano-devices.

[1] Nat. Commun. 8, 407 (2017)