Premium
Magnetic clusters and cluster agglomerations analysed by scanning force microscopy
Author(s) -
von Blanckenhagen P.,
Chao M.,
Gröger R.,
Koch Th.,
Schimmel Th.
Publication year - 2004
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.1686
Subject(s) - magnetic force microscope , cluster (spacecraft) , magnetic field , superparamagnetism , magnet , electromagnet , materials science , chemistry , condensed matter physics , analytical chemistry (journal) , magnetization , physics , quantum mechanics , computer science , programming language , chromatography
Magnetic and non‐magnetic clusters were studied with a scanning force microscope (SFM) equipped with a magnetic tip and a small electromagnet installed at the sample position. The clusters were deposited on freshly cleaved mica surfaces. Heights and diameters of the clusters were determined by analysis of SFM height images. The mean diameter/height ratios show strong differences for the three kind of clusters investigated, however the results are mainly determined by the precisely measured cluster heights. The tip‐sample interaction was analysed by application of the force‐volume mode of operation of the SFM. The comparison of the interaction measured at room temprature on top of different sized cluster agglomerations at different magnetic fields and on the bare substrate surface yielded information on the magnetic state of the cluster systems. Results for magnetic Fe‐ and γ‐Fe 2 O 3 clusters were compared with results for non‐magnetic ZrO 2 clusters. The direct influence of the magnetic field at the sample position on the position of the magnetized tip and of the sample temperature increase due to the magnet current on the SFM results are analyzed and separated experimentally by adjusting appropriate parameters and by subtracting data taken with different parameters. Agglomerations of Fe clusters behaved like systems of soft magnets at temperatures below the blocking temperatures of the systems, whereas those of γ‐Fe 2 O 3 clusters showed superparamagnetic behaviour. The results of this studies indicate that by enable a controlled variation of the sample temprature magnetic phase transitions of cluster systems could be explored in situ as a function of the size of agglomerations by application of scanning probe microscopy. Copyright © 2004 John Wiley & Sons, Ltd.