Exchange interactions with itinerant electrons are known to act as a relaxation mechanism for individual local spins. The same exchange interactions induce the so-called RKKY indirect exchange interaction between two otherwise decoupled local spins. Here, we show that both the spin relaxation and the RKKY coupling can be seen as the dissipative and reactive response to the coupling of the local spins with the itinerant electrons. We thereby predict that the spin relaxation rates of magnetic nanostructures of exchanged coupled local spins, such as nanoengineered spin chains, have an oscillatory dependence on $k_{F}d$, where $k_F$ is the Fermi wave number and $d$ is the interspin distance, very much like the celebrated oscillations in the RKKY interaction. We demonstrate that both $T_1$ and $T_2$ can be enhanced or suppressed, compared to the single-spin limit, depending on the interplay between the Fermi surface and the nanostructure geometrical arrangement. Our results open a route to engineer spin relaxation and decoherence in atomically designed spin structures.

• Received 29 August 2016
• Revised 18 January 2017

DOI:https://doi.org/10.1103/PhysRevB.95.075413