Ultrafast spin transfer and spin logic gates in linear Ni substituted polyacene structures

By using the high-level quantum chemistry method, we investigate the electronic and magnetic properties of Ni substituted polyacene structures as well as the laser-induced ultrafast spin dynamics and related spin logic gates. It is found that among the 61 lowest many-body states for each structure, the states with spin localized on a single magnetic atom mainly concentrate in the lower-energy region, while the states with spin localized on fused benzene rings are located in the higher-energy region. As the acene length becomes longer, the amount of states with spin localization on Ni atoms increases and the possibility of finding states with spin localization on benzene rings gets larger. Through the exploration of laser-induced spin dynamics in these structures, we find that different structures achieve different types of spin-transfer scenarios. Especially, although there exist several states with spin localization on different magnetic atoms for all the structures, the transfer between the two Ni atoms via one Λ process is only achieved in Ni₂(C₁₈H₁₀), Ni₂(C₂₂H₁₂), and Ni₂(C₃₈H₂₀). However, the indirect transfer between two Ni atoms is possible through several bridging Λ processes. Based on the achieved spin scenarios and by appropriately defining the bit information according to the spin localization and directions of the initial and final states, two types of ultrafast spin logic gates, i.e., SWAP and XOR, are constructed. The results obtained in these carbon-based magnetic structures provide valuable insights into their electronic structures and ultrafast spin manipulation and show their potential applications in future molecular spintronic devices and quantum computing.