Excitation of finite size chains of magnetic spin-1/2 atoms adsorbed on a surface by tunneling electrons from a scanning tunneling microscope is studied theoretically in the case of a frustrated ferromagnetic structure of the chain. The magnetic excitation processes are described using the strong coupling approach from Lorente and Gauyacq [Phys. Rev. Lett. 103, 256802 (2009)]. Varying the exchange-coupling parameters, the chain length and the strength of an applied magnetic field generates a broad variety of magnetic structures in the chain. The links between these various structures and the excitation processes by tunneling electrons are presented, together with a discussion on how the magnetic structure of a chain could be inferred from an inelastic electron tunneling experiment. Extrapolation of the finite size calculations to infinite chains leads to a discussion of the characteristics of the spin waves that can be excited by tunneling electrons in these frustrated magnetic systems.

• Received 5 May 2011

DOI:https://doi.org/10.1103/PhysRevB.84.085415