Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 67: Oxides and Insulator Surfaces: Structure, Epitaxy and Growth
(Joint session of O and TT organized by O)

TT 67.7: Vortrag

Donnerstag, 10. März 2016, 12:15–12:30, H4

Two-Dimensional Iron Tungstate Honeycomb Layers on Pt(111) — •Sascha Pomp¹, David Kuhness¹, Giovanni Barcaro², Luca Sementa², Alessandro Fortunelli², Martin Sterrer¹, Falko P. Netzer¹, and Svetlozar Surnev¹ — ¹Institute of Physics, University of Graz, A-8010 Graz, Austria — ²CNR-ICCOM & IPCF, Consiglio Nazionale delle Ricerche, I-56124 Pisa, Italy

We report the first example of a 2D ternary oxide layer with a honeycomb geometry identified as FeWO3, which has no bulk analogue. The 2D iron tungstate phase described here has been synthesized in UHV via a solid state reaction of (WO3)3 clusters with a FeO monolayer on a Pt(111) surface. It has been characterized by a variety of surface analytic techniques, involving x-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), low-energy electron diffraction (LEED) and temperature programmed desorption (TPD), combined with density functional theory (DFT) calculations. Consistent with the experimental results, the DFT calculations show that the FeWO3 layer consists of a mixed layer of Fe and W atoms, formally Fe2+ and W4+ species, sitting in fcc and hcp Pt hollow sites, respectively, and arranged in a (2x2) superstructure. This layer is terminated by oxygen atoms in Fe-W bridging positions, forming a buckled honeycomb lattice. In addition the DFT calculations predict that the 2D FeWO3 layer exhibits ferromagnetic order with a Curie temperature of 95 K, as opposed to the antiferromagnetic behavior in the bulk FeWO4 phase.