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)