In this paper, we present a new generation of Nanocrystalline magnetic cores (kμ) with low permeability. The magnetic properties of kμ magnetic cores will be compared to other magnetic cores which have the same range of relative magnetic permeability. The kμ magnetic cores allow magnetic core volume (resp. core mass) to be reduced by up to 5.5 times (resp. by up to 3 times) compared to Ferrite magnetic core. Moreover, no air gap is needed in such core to get low μ, so no electromagnetic perturbation will be emitted by the core. Exhibiting also high cut-off frequency, low magnetic losses, low magnetostriction or high B-H linearity, the kμ magnetic cores appear as a new and efficient product for passive component integration or embedded electronics.