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G. Parkinson:
"There´s Life in the Old Dog Yet: New Insights from the Earth´s Oldest Known Magnetic Material (Fe₃O₄)";
Vortrag: Seminar Institut für Allgemeine Physik (IAP), TU Wien, Institut für Angewandte Physik; 04.06.2013.

Magnetite (Fe3O4), the material through which mankind first encountered magnetism, continues to fascinate scientists with its remarkable properties. In this seminar I will present two very different recent highlights from our magnetite project. Firstly, a combination of scanning tunneling microscopy (STM) and spin polarized low-energy electron microscopy (SP-LEEM) sheds new light on how the (bulk) Verwey metal-insulator transition affects the Fe3O4(001) surface. In the insulating low temperature phase a roof-like structure with a periodicity of ~0.5 µm emerges as a consequence of micro-twinning within ferroelastic domains. The "Verwey roof", as we call it, is visible as dark-light stripes in SP-LEEM images, allowing the structural and magnetic domains to be studied in real-time.
In the second part of the talk I will show how gas molecules can induce atom mobility at surfaces. Specifically, I will demonstrate that the adsorption of CO causes initially stable Pd adatoms to rapidly diffuse on the Fe3O4(001) surface. Using atomically resolved STM movies we follow individual Pd-CO species across the surface and directly observe the atomic-scale details of cluster nucleation and growth for the first time.