PhD Thesis Defense- Iker Gallardo
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PhD Thesis Defense- Iker Gallardo
CFM Seminars
- Speaker
-
Iker Gallardo
- When
-
2019/11/04
12:00
- Place
- CFM First Flor Seminar Room
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![PhD Thesis Defense- Iker Gallardo](/++theme++dipc-theme/img/event_image_gorria.png)
**Title: Magnetic properties of Co on different environments**
**Supervisors: **Andres Arnau and Fernando Delgado
**Research group: **Modelisation and Simulation group **
**
**When:** November 4, 2019 (11:00h)
**Where:** CFM SEMINAR ROOM
[ **Download
pdf**](https://cfm.ehu.es/view/files/Phd_Thesis_Iker_Gallardo.pdf)
### **Summary**
We combine density functional theory (DFT) calculations and a multiorbital
many-body Hamiltonian approach to shed light on magnetic properties of Co
adsorbed on h-BN depending on the adsorption site. These methods reveal an
out-of-plane easy axis anisotropy for atop N site and hard axis for hollow
site, with an electronic configuration close to 3d8, corresponding to a spin S
= 1. Then, we compare our results with x-ray absorption spectroscopy (XAS),
x-ray magnetic circular dichroism (XMCD) and x-ray magnetic linear dichroism
(XMLD) measurements on Co/h-BN/Ir(111) and Co/h-BN/Ru(0001). XAS and XMCD data
show large (14 meV) out-of-plane anisotropy for Co/h-BN/Ru(0001) and almost
isotropic for Co/h-BN/Ir(111), while both have an electronic structure
compatible with spin S = 1. We use this information to determine the atop N
adsorption of Co on h- BN/Ru(0001) and hollow for the Co on h-BN/Ir(111). XMLD
data together with DFT and multiorbital Hubbard model results suggest that the
different adsorption sites induce dissimilar anisotropy of Co. Finally, we
explain from DFT calculations the counterintuitive downward shift of the
Au(111) surface state measured by angle resolved photo-emission spectroscopy
(ARPES) when two homothetic Co-coordinated metal-organic nanoporous networks
(MONN) are self-assembled. We associate this effect to the weak Co-substrate
hybridization and show that it appears with different adatoms and substrates.
![](https://cfm.ehu.es/view/files/h-BN_Ru0001.png)
Top views of the 4 4 supercell for h-BN on Ir(111) surface, after relaxation
of the h-BN monolayer in the Z direction. Green and blue spheres represent B
and N atoms, respectively, while light blue are the top most layer Ir(111)
surface atoms.