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Magnetic fluctuations of the very small

Friday, October 20, 2017 - 12:00
Place: 
CFM Auditorium
Who: 
Julen Ibañez-Azpiroz (CFM)
Source Name: 
CFM

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. Ibañez-Azpiroz et al., Nano Lett. 16, 4305 (2016).



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