In this thesis, the properties of magnetotransport of novel Dirac systems are outlined on the example of Weyl semimetals and carbon nanotubes with side-attached single-molecule magnets. In Weyl semimetals, we discussed the effects of impurities on transport showing that in both in absence and in presence of a finite magnetic field impurities can strongly affect the transport properties. Moreover, we showed that the experimentally observed huge transversal magnetoresistance in Weyl semimetals can be explained by a model of shifted Weyl nodes in energy with respect to each other in presence of Coulomb impurities. Related to the carbon nanotube system, we provided a theoretical model to describe the gate-controlled spin-valve effect and giant magnetoresistance. The important ingredients of the model are Coulomb interaction and spin dependent resonant scattering on Fano resonances between barriers.