Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 63: [MA] Surface magnetism III
O 63.5: Vortrag
Donnerstag, 17. März 2011, 12:00–12:15, HSZ 103
Antiferromagnetic Mn chains on Ni(110) — •Simon Holzberger, Tobias Schuh, and Wulf Wulfhekel — Physikalisches Institut, Karlsruher Institut für Technologie, Germany
A novel even-odd effect has recently been predicted for atomic manganese chains supported
by a ferromagnetic substrate [1]. While odd chains possess a net spin that aligns
according to the coupling to the substrate resulting in a collinear spin state, even
chains display a non-collinear state.
To investigate atomic chains experimentally, low-temperature spin-polarized scanning
tunneling microscopy (Sp-STM) was used. To favor the growth of linear chains, a
ferromagnetic Ni(110) surface was chosen as substrate. While self assembly of chains by
thermal diffusion always led to intermixing with the substrate, pure manganese chains
could be created by atomic manipulation. The electronic structure of the chains was
investigated by scanning tunneling spectroscopy revealing a strong dependence on
the length of the chain. This is explained within the model of an unoccupied quasi
atomic state in single manganese adatoms.
Sp-STM confirmed the predicted collinear antiferromagnetic ground state for linear
trimers. In contrast to the calculations, however, there was no indication of an
antiferromagnetic or non-collinear spin structure for even-numbered chains. This
observation is explained by the degeneracy of the antiferromagnetic ground state
highlighting the quantum nature of the magnetic state.
[1] S. Lounis et al., Phys. Rev. Lett. 101, 107204 (2008)