Indirect exchange coupling between localized magnetic moments in carbon nanotubes: a dynamic approach

TL;DR

This paper investigates how the dynamic precession of magnetic moments in carbon nanotubes enhances the range of indirect exchange coupling, with potential applications in large-scale spintronics devices.

Contribution

It introduces a dynamic approach to analyze indirect exchange coupling, revealing that precessional motion significantly extends the interaction range compared to static cases.

Findings

Precessional motion increases the effective range of magnetic coupling.

Resonant peaks in spin susceptibility indicate stronger dynamic interactions.

Dynamic coupling could enable new spintronics device functionalities.

Abstract

Magnetic moments dilutely dispersed in a metallic host tend to be coupled through the conduction electrons of the metal. This indirect exchange coupling, known to occur for a variety of magnetic materials embedded in several different metallic structures, is of rather long range, especially for low-dimensional structures like carbon nanotubes. Motivated by recent claims that the indirect coupling between magnetic moments in precessional motion has a much longer range than its static counterpart, here we consider how magnetic atoms adsorbed to the walls of a metallic nanotube respond to a time-dependent perturbation that induces their magnetic moments to precess. By calculating the frequency-dependent spin susceptibility we are able to identify resonant peaks whose respective widths provide information about the dynamic aspect of the indirect exchange coupling. We show that by departing from a purely static representation to another in which the moments are allowed to precess, we change from what is already considered a long range interaction to another whose range is far superior. In other words, localized magnetic moments embedded in a metallic structure can feel each other's presence more easily when they are set in precessional motion. We argue that such an effect can have useful applications leading to large-scale spintronics devices.