RKKY oscillations in the spin relaxation rates of atomic scale nanomagnets

TL;DR

This paper predicts that spin relaxation rates in atomic-scale nanomagnets exhibit oscillations dependent on Fermi wavelength and inter-spin distance, linking relaxation dynamics with RKKY interactions and enabling engineered spin decoherence control.

Contribution

It introduces a unified response framework showing both spin relaxation and RKKY coupling as related dissipative and reactive effects, revealing oscillatory behavior in relaxation rates.

Findings

Spin relaxation rates oscillate with $k_F d$, similar to RKKY interactions.

Both $T_1$ and $T_2$ can be tuned via nanostructure geometry.

Results suggest pathways to engineer spin decoherence in atomically designed structures.

Abstract

Exchange interactions with itinerant electrons are known to act as a relaxation mechanism for individual local spins. The same exchange interactions are also known to 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 as nanoengineered spin chains, have an oscillatory dependence on $k_F d$ , where $k_F$ is the Fermi wave length and $d$ is the inter-spin 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.