Jungiusstr. 11, Hörsaal AP
SFB 668 - Kolloquium
Assistant Prof. Dr. Mircea V. Rastei (Université de Strasbourg) :
Revealing Magnetic Properties of Single Nanoscale Objects by Scanning Probe Techniques: from submicron dots to molecules and atoms
Magnetic properties of single nanoscale objects became a major scientific focus due to their potential for applications in magnetic devices or clinical diagnosis and therapy. This topic is however of great complexity, essentially because the magnetic properties depend on various parameters such as object?s size, shape, crystallographic and electronic structure, but also on and the local medium to which the nanoscale objects belong. Scanning probe techniques represent so far a unique experimental approach capable to reveal correlated information on these parameters and the single-object magnetic properties.
I will present first an approach in which Field-Dependent Magnetic Force Microscopy ( FD-MFM ) is used in order to reveal magnetization characteristics of single nanodots. In particular, I will show that an integral value of the cantilever phase shift obtained in vibrating MFM experiment can be used as a measure of the field-dependent magnetization direction of single CoPt and Co nanodots. Afterwards, I will present results obtained by Spin-Polarized Scanning Tunneling Microscopy and Spectroscopy ( SP-STM and SP-STS ) on smaller objects, such as Co nanoislands and molecules. Here, I will also discuss to which extent spin-polarized electronic states are influenced by minute changes of the crystallographic structure such as strain and stacking order. In this respect, a way for tuning the spin-polarized states at surfaces will be presented. Several studies from the literature reflecting recent progress in the field will be also highlighted.