Based on the direct observation of vacuum tunneling of spin‐polarized electrons by means of a scanning tunneling microscope (STM) with a ferromagnetic CrO2 tip, it has been possible to probe the alternating magnetization of different terraces of a Cr(001) surface on a nanometer scale.1,2 More recently, we have achieved even atomic resolution in magnetic‐sensitive STM studies of Fe3O4 (001) surfaces by using atomically sharp, insitu prepared Fe probe tips.3,4 An atomic‐scale contrast between the different magnetic ions Fe(2+) and Fe(3+) in magnetite has been detected with these Fe tips which is not present by using nonmagnetic W tips.5 The experimental results based on magnetic‐sensitive STM and local tunneling spectroscopy indicate the presence of a Wigner glass state at the Fe3O4 (001) surface at room temperature. The perspectives of atomic‐resolution magnetic‐sensitive STM studies for the characterization of magnetic surfaces, ultra‐thin films, and multilayers in general will be discussed.

1.
R.
Wiesendanger
,
H.-J.
Giintherodt
,
G.
Giintherodt
,
R. J.
Gambino
, and
R.
Ruf
,
Phys. Rev. Lett.
65
,
247
(
1990
).
2.
R.
Wiesendanger
,
D.
Biirgler
,
G.
Tarrach
,
A.
Wadas
,
D.
Brodbeck
,
H.-J.
Giintherodt
,
G.
Giintherodt
,
R. J.
Gambino
, and
R.
Ruf
,
J. Vac. Sci. Technol. B
9
,
519
(
1991
).
3.
R.
Wiesendanger
,
I. V.
Shvets
,
D.
Burgler
,
G.
Tarrach
,
H.-J.
Giintherodt
, and
J. M. D.
Coey
,
Z. Phys. B
86
,
1
(
1992
).
4.
R.
Wiesendanger
,
I. V.
Shvets
,
D.
Burgler
,
G.
Tarrach
,
H.-J.
Giintherodt
, and
J. M. D.
Coey
,
Science
255
,
583
(
1992
).
5.
R.
Wiesendanger
,
I. V.
Shvets
,
D.
Burgler
,
G.
Tarrach
,
H.-J.
Giintherodt
, and
J. M. D.
Coey
,
Europhys. Lett.
19
,
141
(
1992
).
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