ABSTRACT
Recent magnetic applications focus on nanometre scale devices such as spin
valves, magnetic random access memory or high density magnetic storage media.
Much effort is being devoted to spin dependent ab initio calculations of the mag-
netic order near magnetic domain walls and grain boundaries. Hand-in-hand with
simulations improved experimental methods are also approaching nanometre
scale analysis of magnetic properties. Although the ultimate goal is imaging mag-
netic moments on the atomic scale, a spatial resolution of less than 2 nm in EMCD
analysis on an Fe/Au multilayer stack could be demonstrated [Schattschneider
et al. (2008b)], preparing the way to the ultimate goal: imaging magnetic moments
in the bulk material on the atomic scale. Such high spatial resolution can be
achieved in the TEM in two ways. The TEM is operated either in scanning mode
(Scanning TEM — STEM) or in imaging mode. The scanning mode has some
advantages over the conventional imaging mode. The most obvious advantage
is that working in STEM allows us to obtain two extra signals in addition to the
EMCD signal in the same experiment. These are energy dispersive X-ray analysis
(EDX) and Z-contrast imaging using a high-angle annular dark field (HAADF)
detector (see for example Batson (1992)). Modern machines have both modes
of operation, TEM and STEM, and are called (S)TEM. Recent high-end (S)TEM
instruments have aberration-corrected lens systems, such that spherical aberration
are reduced to negligible levels for the condenser system (probe Cs corrector) [Krivanek et al. (1999)] and for the objective lens system (image Cs corrector) [Rose
(1999)]. Switching between TEM and STEM mode is relatively easy.
