Abstract 1 July 2015

Magnetic excitations and electronic currents on the atomic scale

Nicolas Lorente, Centro de Física de Materiales (CSIC), Donostia International Physics Center, San Sebastián, Spain

The scanning tunneling microscope (STM) is instrumental when analyzing matter on the atomic scale. Not only has it sub-atomic spatial resolution, but it is well below the milli-eV energy scale, which allows it to map the spectral function of complex systems with unprecedented resolution. The advent of milli-Kelvin techniques is also of fundamental importance when studying magnetism on the nanoscale. An emerging full field of magnetic inelastic electron spectroscopy (IETS) [1] is permitting us to unravel the microscopic origin of magnetism on the nanoscale. Our work deals with the understanding and numerical simulation of all these phenomena. I will present numerical studies on metallic phthalocyanine molecules on Ag (100) [2] which gives unprecedented insight in molecular magnetism on a non-magnetic host. Correlations, high spins and the Kondo effect can be found here. Excitations are naturally seen by the STM-based experiments, and excitations are very interesting when combined with the Kondo effect [3]. I will talk about the intrinsic correlations appearing in anfiferromagnets, and how this leads to a handle on spin manipulations [4]. To finish
this general overview of magnetism on the nanoscale, I will present our calculations on the spin filtering effect of a molecular magnet and how magnetic excitations become crucial [5].

[1] C.F. Hirjibehedin, C.-Y. Lin, A.F. Otte, M. Ternes, C.P. Lutz, B.A. Jones, and A.J. Heinrich,
Science 317, 1199 (2007).
[2] A. Mugarza, N. Lorente, P. Ordejón, C. Krull, S. Stepanow, M.-L. Bocquet, J. Fraxedas, G.
Ceballos, and P. Gambardella, Phys. Rev. Lett. 105, 115702 (2010); A. Mugarza, R. Robles, C.
Krull, R. Korytár, N. Lorente, and P. Gambardella, Phys. Rev. B 85, 155437 (2012).
[3] Richard Korytár, Nicolás Lorente and Jean-Pierre Gauyacq, Phys. Rev. B 85, 125434 (2012).
[4] J.-P. Gauyacq, S. M. Yaro, X. Cartoixà, N. Lorente, Phys. Rev. Lett. 110, 087201 (2013).
[5] P.N. Abufager, R. Robles, N. Lorente, J. Phys. Chem. C. 119, 12119 (2015).

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