Ruderman-Kittel-Kasuya-Yosida-Type Interlayer Dzyaloshinskii-Moriya Interaction in Synthetic Magnets.

Conduction electron spins interacting with magnetic impurity spins can mediate an interlayer exchange interaction, namely, the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. This discovery opened the way to significant technological developments in the field of magnetic storage and spintronics. So far, the RKKY-type interlayer interaction has been found to construct symmetric coupling of magnetism; however, the asymmetric counterpart remains unexplored. Here we report unprecedented RKKY-type interlayer Dzyaloshinskii-Moriya interaction (DMI) in synthetic magnets, exhibiting a damped oscillatory feature. This asymmetric interlayer interaction is found to be dramatically dependent on the intermediate coupling layer. By introducing the Fert-Lévy model to the trilayer system, we reveal that the in-plane inversion symmetry breaking plays a pivotal role for generating interlayer DMI and the RKKY oscillation is an intrinsic behavior in metallic multilayers. Our finding fills up the empty block for RKKY-type asymmetric interlayer exchange coupling in comparison to the well-known (symmetric) RKKY-type interlayer exchange coupling.