Spin transport in carbon nanotubes with magnetic vacancy-defects

The spin-polarized electron transport properties of metallic carbon nanotubes containing vacancies are investigated using first-principles and nonequilibrium Green's function techniques. Reconstructed mono- and trivacancies, containing carbon atoms with unsaturated bonds, behave like quasilocalized magnetic impurities. However, in conventional ab initio simulations, these magnetic defects are artificially repeated periodically (supercell method) and are thus incorrectly coupled by long range interactions. Consequently, a technique based on an open system with an isolated magnetic impurity is used here to accurately describe the local magnetic properties of these defects, revealing spin-dependent conductances in tubes, which could be exploited in spintronic nanodevices.