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MA: Fachverband Magnetismus
MA 60: Spin Structures and Magnetic Phase Transitions
MA 60.1: Talk
Thursday, March 17, 2011, 17:30–17:45, HSZ 103
Imaging the ferromagnetic phase transition in magnetic microstructures with PEEM — •Oliver Sandig1, Julia Herrero-Albillos1, Nils Nüsse1, Florian Kronast1, Florian M. Römer2, and Michael Farle2 — 1Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin — 2Universität Duisburg-Essen, Duisburg
A fundamental question in ferromagnetic systems with reduced dimensions is, whether magnetic properties vary laterally at the edges of the sample, at defects or at steps due to the underlying substrate. Due to changes in the local fluctuation rate of the magnetic moments, the Curie Temperature (TC) is a good quantity to detect such variations. Those changes of TC and the involved length scales are of increasing interest for the stability of data storage and spintronic applications. We used x-ray photoelectron emission microscopy to image local variations of TC in micro-structured Fe films. We grew well defined magnetic structures of different shape and size by in-situ Fe evaporation on pre-patterned Si substrates. Different areas on our sample were magnetically decoupled from each other due to the sample topography. To image local variations of TC we used a special sample holder. It allows measuring the local AC susceptibility (χac) as a function of temperature with a spatial resolution better than 100nm and temperature stability of 0.2K [1]. In our presentation we compare TC of different magnetic structures to that of a continuous reference film which allows us to identify the onset of finite size effects in our sample.