Dresden 2017 – scientific programme

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MA: Fachverband Magnetismus

MA 22: Surface Magnetism (Joint Session with O)

MA 22.1: Invited Talk

Tuesday, March 21, 2017, 09:30–10:00, HSZ 401

Tuning the zero-point spin-fluctuations of single adatoms — •Julen Ibañez-Azpiroz — Peter Grünberg Institut and Institute of Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany

Single-adatoms deposited on metallic substrates offer an exceptional playground for studying magnetism at the atomic scale and give rise to several intriguing questions. For instance, although several adatoms exhibit a large magnetic anisotropy energy as measured by X-ray Magnetic Circular Dichroism [1], the very same adatoms behave as paramagnetic objects when probed by Scanning Tunneling Spectroscopy (STS) [2, 3]. Motivated by this apparent contradiction, we analyze the role of quantum fluctuations of the adatom’s spin at T=0, the so-called zero-point spin-fluctuations (ZPSF) utilizing time-dependent density functional theory [4]. We investigate several 3d and 4d magnetic adatoms on different substrates, accessing the magnitude of ZPSF and identifying the underlying physical mechanism as well as their implication on the magnetic stability. Remarkably, while spin-fluctuations weaken magnetism, they could be used to detect magnetic signals even in non-magnetic adatoms. We show that the latter can exhibit intense paramagnetic spin-excitations easily tunable with a magnetic field and potentially observable with inelastic STS [5].

[1] P. Gambardella etal., Science 300, 1130 (2003). [2] L. Zhou etal., Nat. Phys. 6, 187 (2010). [3] A. A. Khajetoorians, etal., PRL 106, 037205 (2011). [4] J. Ibañez-Azpiroz etal., Nano Lett. (2016), 10.1021/acs.nanolett.6b01344 [5] J. Ibañez-Azpiroz etal., in prep.