We observed unexpected resonant response in $[\mathrm{Fe}/\mathrm{Cr}{]}_{10}$ multilayers epitaxially grown on MgO(100) substrates which exists only when both ac current and dc magnetic field are simultaneously applied. The magnitude of the resonances is determined by the multilayer magnetization proving their intrinsic character. The reduction of interface epitaxy leads to nonlinear dependence of the magnitude of resonances on the alternating current density. We speculate that the existence of the interface transition zone could facilitate the subatomic vibrations in thin metallic films and multilayers grown on bulk insulating substrates.

• Received 22 February 2008

DOI:https://doi.org/10.1103/PhysRevLett.102.035503