Structural, electronic and magnetic properties of the 3d transition-metal-doped AlN nanotubes

We have performed the first-principles calculations onto the structural, electronic and magnetic properties of seven 3d transition-metal (TM) impurities (V, Cr, Mn, Fe, Co, Ni and Cu) doped armchair (5,5) and zigzag (8,0) aluminum nitride nanotubes (AlNNTs). The results show that, there exists a structural distortion around 3d TM impurities with respect to the pristine AlNNTs. The magnetic moment increases for V-, Cr- and Mn-doped AlNNTs successively and reaches maximum for Fe-doped AlNNTs, and then decreases for Co-, Ni- and Cu-doped AlNNTs successively, consistent with the predicted trend of the Hundʹs rule to maximize the magnetic moments of the doped TM ions. However, the values of the magnetic moments are smaller than the predicted values of Hundʹs rule due to strong hybridization between p orbitals of near N and Al atoms of AlNNTs and d orbitals of the TM ions. Furthermore, the V- and Ni-doped (5,5) and (8,0) AlNNTs with half-metal and thus 100% spin-polarization characters seem to be good candidates for spintronic applications.