Transition metal induced magnetism in smaller fullerenes (Cn for n≤36).

The magnetic properties of 3d transition metals (TM) encapsulated inside smaller fullerenes ranging from C20 to C36 have been investigated using spin polarized density functional theory. The TM impurities stabilize asymmetrically at an off-center position for n≥28. The total magnetic moment (MM) of TM@Cn complexes are largely contributed by TMs and a small amount of MM of 0.12-0.50 μB is induced on the cage carbon atoms. The 3d TM atoms interact with C atoms of C20 and C28 cage ferromagnetically (FM) except for Ni@C28 which shows antiferromagnetic (AFM) interaction. The magnetic interactions change from FM to AFM in C32 cage for Ti, V, Cr and Mn. The MM gets quenched in Ni@Cn for n≥32. The total MM of Mn@Cn does not show any change although the nature of magnetic interactions changes from FM to AFM at n=32. Ti and V are the only TMs which show positive cohesive energy in all fullerenes considered. The smallest fullerene which can encapsulate all 3d TM are Cn for n≥32, consistent with available experimental and theoretical results.