Magnetic Frustration in Nanowires: Domino Effect

The parity of the number of atoms in finite antiferromagnetic nanowires deposited on ferromagnetic substrates is shown to be crucial in predicting whether the magnetic ground state is non-collinear or collinear [1]. Using the full-potential Korringa-Kohn- Rostoker method for non-collinear magnetism [2] and a Heisenberg model we show that the magnetic structure of the whole nanowires dramatically changes if a {\em single} adatom is added. Infinite and finite nanochains with even number of adatoms are always magnetically non-collinear while odd numbers of atoms in the wire lead under given conditions to a collinear ferrimagnetic ground state. This unexpected nano-effect, which resembles a domino-effect, occurs only for wires at finite lengths. [1] S. Lounis, P. H. Dederichs, S. Blügel, Phys. Rev. Lett. 101, 107204 (2008). [2] S. Lounis, Ph. Mavropoulos, P. H. Dederichs, S. Blügel, Phys. Rev. B 72 224437 (2005).