In the appropriate size range it can be argued that the absolute value of a negative curling nucleation field in a prolate spheroid is a good approximation for the switching field in any regularly shaped ferromagnetic body, which has the same volume, provided the correct demagnetizing field is used. An example is given for the case of a square prism. The discrepancy between this theory and some experimental results is claimed to be due to volume and surface anisotropies in the experimental particles.

1.
A. Aharoni, Introduction to the Theory of Ferromagnetism (Oxford University Press, New York, 1996), Chaps. 9 and 11.
2.
M. E.
Schabes
and
H. N.
Bertram
,
J. Appl. Phys.
64
,
1347
(
1988
);
M. E.
Schabes
,
J. Magn. Magn. Mater.
95
,
249
(
1991
).
3.
M. E.
Schabes
and
A.
Aharoni
,
IEEE Trans. Magn.
23
,
3882
(
1987
).
4.
A.
Aharoni
, in
Proceedings of the Magnetism of Nanostructured Phases Conference
[
J. Magn. Magn. Mater.
203
,
33
(
1999
)].
5.
C.
Seberino
and
H. N.
Bertram
,
IEEE Trans. Magn.
33
,
3055
(
1997
).
6.
H. N.
Bertram
and
C.
Seberino
,
J. Magn. Magn. Mater.
193
,
388
(
1999
).
7.
A. E.
Berkowitz
,
E. L.
Hall
, and
P. J.
Flanders
,
IEEE Trans. Magn.
23
,
3816
(
1987
).
8.
A.
Aharoni
,
J. Appl. Phys.
83
,
3432
(
1998
).
9.
W.
Rave
,
K.
Ramstöck
, and
A.
Hubert
,
J. Magn. Magn. Mater.
183
,
329
(
1998
).
10.
A.
Thiaville
,
D.
Tomás̆
, and
J.
Miltat
,
Phys. Status Solidi (a)
170
,
125
(
1998
).
11.
W.
Rave
,
K.
Fabian
, and
A.
Hubert
,
J. Magn. Magn. Mater.
190
,
332
(
1998
).
12.
http://www.ctcms.nist.gov/rdm/mumag.html, results of Standard Problem #3.
13.
A.
Hubert
and
W.
Rave
,
Phys. Status Solidi (b)
211
,
815
(
1999
).
14.
A. J.
Newell
and
R. T.
Merrill
,
J. Appl. Phys.
84
,
4394
(
1998
).
15.
D. F.
Eagle
and
J. C.
Mallinson
,
J. Appl. Phys.
38
,
995
(
1967
).
16.
A.
Aharoni
,
IEEE Trans. Magn.
27
,
4775
(
1991
).
17.
A.
Aharoni
,
J. Appl. Phys.
82
,
1281
(
1997
).
18.
R.
Ferré
,
K.
Ounadjela
,
J. M.
George
,
L.
Piraux
, and
S.
Dubois
,
Phys. Rev. B
56
,
14
066
(
1997
).
19.
W.
Wernsdorfer
,
B.
Doudin
,
D.
Mailly
,
K.
Hasselbach
,
A.
Benoit
,
J.
Meier
,
J.-Ph.
Ansermet
, and
B.
Barbara
,
Phys. Rev. Lett.
77
,
1873
(
1996
).
20.
P. F.
Fulmek
and
H.
Hauser
,
J. Appl. Phys.
76
,
6561
(
1994
).
21.
A.
Aharoni
,
J. Phys.: Condens. Matter
9
,
10
009
(
1997
).
22.
D. R.
Fredkin
and
T. R.
Koehler
,
IEEE Trans. Magn.
25
,
3473
(
1989
);
D. R.
Fredkin
and
T. R.
Koehler
,
J. Appl. Phys.
67
,
5544
(
1990
).
23.
C.
Yang
,
J. M.
Siversten
, and
J. H.
Judy
,
IEEE Trans. Magn.
32
,
3837
(
1996
).
24.
R.
O’Barr
,
M.
Lederman
,
S.
Schultz
,
W.
Xu
,
A.
Scherer
, and
R. J.
Tonucci
,
J. Appl. Phys.
79
,
5303
(
1996
).
25.
R.
O’Barr
and
S.
Schultz
,
J. Appl. Phys.
81
,
5458
(
1997
).
26.
A.
Aharoni
,
J. Appl. Phys.
35
,
347
(
1964
).
27.
A.
Aharoni
,
IEEE Trans. Magn.
5
,
207
(
1969
).
28.
A.
Aharoni
,
J. Magn. Magn. Mater.
196-7
,
786
(
1999
).
29.
A.
Aharoni
,
J. Appl. Phys.
61
,
3302
(
1987
).
30.
A.
Aharoni
,
J. Appl. Phys.
64
,
6434
(
1988
).
31.
K.
Zhang
and
D. R.
Fredkin
,
J. Appl. Phys.
79
,
5762
(
1996
).
32.
A.
Aharoni
and
E.
Neeman
,
Phys. Lett.
6
,
241
(
1963
).
33.
R. W.
De Blois
,
J. Appl. Phys.
32
,
1561
(
1961
).
34.
W. Wernsdorfer (private communication).
This content is only available via PDF.
You do not currently have access to this content.