Coherent ultrafast local spin-switching ΛΛ processes in chainlike nanostructures with two identical magnetic centers

The laser-induced ultrafast spin-switching mechanism via ΛΛ processes in chainlike nanostructures with two identical magnetic centers (here Co atoms) is systematically investigated using a fully ab initio   method. In our recent paper [Physical Review B 84 (2011) 054415], a series of rules of thumb was obtained for spin-switching and spin-transferring ΛΛ processes in charged linear molecular ions with two different magnetic centers. In the present work, the theory is further developed and focuses on neutral systems with two identical magnetic centers. It is found that the chromophore CO molecule plays a critical role in the spin localization in the system by lowering its symmetry. Using Mg as a bridging atom we achieve the so far fastest spin-switching scenario (within 100 fs, an increase in speed by a factor of 3). This demonstrates the necessity for careful engineering of spin-logic units in future nanoscale spintronic devices.

► Laser-induced ultrafast spin-switching mechanism via ΛΛ processes is presented. ► A fully ab initio method is adopted in the present theoretical investigation. ► Neutral chainlike nanostructures with two identical magnetic centers are studied. ► The so far fastest spin-flip scenario (within 100 fs) via a ΛΛ process is achieved. ► Both the CO and the bridging atom Mg play important roles in spin localization.