"Magnetic fluctuations of the very small "

Who: Julen Ibaņez-Azpiroz (CFM)

Place: CFM Auditorium

Date: Friday, 20 October 2017, 12:00

Single-adatoms deposited on metallic substrates offer an exceptional playground for studying magnetism at the atomic scale and give rise to many 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 utilizing time-dependent density functional theory [4]. Remarkably, while spin-fluctuations weaken magnetism, they can be used to detect magnetic signals even in non-magnetic adatoms, which can exhibit intense paramagnetic spin-excitations tunable with a magnetic field and potentially observable with inelastic STS [5].

[1] P. Gambardella et al., Science 300, 1130 (2003).

[2] L. Zhou et al., Nat. Phys. 6, 187 (2010).

[3] A. A. Khajetoorians, et al., PRL 106, 037205 (2011).

[4] J. Ibaņez-Azpiroz et al., Nano Lett. 16, 4305 (2016).

[5] J. Ibaņez-Azpiroz et al., PRL 119, 017203 (2017)

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