We report the controlled integration, via dip pen nanolithography, of monolayer dots of ferritin-based CoO nanoparticles (12 μB) into the most sensitive areas of a microSQUID sensor. The nearly optimum flux coupling between these nanomagnets and the microSQUID improves the achievable sensitivity by a factor 102, enabling us to measure the linear susceptibility of the molecular array down to very low temperatures (13 mK). This method opens the possibility of applying ac susceptibility experiments to characterize two-dimensional arrays of single molecule magnets within a wide range of temperatures and frequencies.

1.
F.
Luis
,
F.
Bartolomé
,
F.
Petroff
,
J.
Bartolomé
,
L. M.
García
,
C.
Deranlot
,
H.
Jaffrès
,
M. J.
Martínez
,
P.
Bencok
,
F.
Wilhelm
,
A.
Rogalev
, and
N. B.
Brookes
,
Europhys. Lett.
76
,
142
(
2006
).
2.
J. M.
Hernández
,
X. X.
Zhang
,
F.
Luis
,
J.
Bartolomé
,
J.
Tejada
, and
R.
Ziolo
,
Europhys. Lett.
35
,
301
(
1996
).
3.
E. M.
Chudnovsky
and
J.
Tejada
,
Macroscopic Quantum Tunneling of the Magnetic Moment, Cambridge Studies in Magnetism
(
Cambridge University Press
,
Cambridge
,
1998
).
4.
D.
Gatteschi
,
R.
Sessoli
, and
J.
Villain
,
Molecular Nanomagnets
(
Oxford University Press
,
Oxford
,
2006
).
5.
D. D.
Awschalom
,
J. R.
Rozen
,
M. B.
Ketchen
,
W. J.
Gallagher
,
A. W.
Kleinsasser
,
R. L.
Sandstrom
, and
B.
Bumble
,
Appl. Phys. Lett.
53
,
2108
(
1988
).
6.
W.
Wernsdorfer
,
K.
Hasselbach
,
D.
Mailly
,
B.
Barbara
,
A.
Benoit
,
L.
Thomas
, and
G.
Suran
,
J. Magn. Magn. Mater.
145
,
33
(
1995
).
7.
S. K. H.
Lam
and
D. L.
Tilbrook
,
Appl. Phys. Lett.
82
,
1078
(
2003
).
8.
J. P.
Cleuziou
,
W.
Wernsdorfer
,
V.
Bouchiat
,
T.
Ondarcuhu
, and
M.
Monthioux
,
Nat. Nanotech.
1
,
53
(
2006
).
9.
L.
Hao
,
C.
Amann
,
J. C.
Gallop
,
D.
Cox
,
F.
Ruede
,
O.
Kazakova
,
P.
Josephs-Franks
,
D.
Drung
, and
Th.
Schurig
,
Appl. Phys. Lett.
98
,
092504
(
2011
).
10.
V.
Bouchiat
,
Supercond. Sci. Technol.
22
,
064002
(
2009
).
11.
S. K. H.
Lam
,
W.
Yang
,
H. T. R.
Wiogo
, and
C. P.
Foley
,
Nanotechnology
19
,
285303
(
2008
).
12.
L.
Bogani
,
C.
Danieli
,
E.
Biavardi
,
N.
Bendiab
,
A. L.
Barra
,
E.
Dalcanale
,
W.
Wernsdorfer
, and
A.
Cornia
,
Angew. Chem. Int. Ed.
48
,
746
(
2009
).
13.
R. D.
Piner
,
J.
Zhu
,
F.
Xu
,
S.
Hong
,
C. A.
Mirkin
,
Science
283
,
661
(
1999
).
14.
S.
Sekula
,
J.
Fuchs
,
S.
Weg-Remers
,
P.
Nagel
,
S.
Schuppler
,
J.
Fragala
,
N.
Theilacker
,
M.
Franzreb
,
C.
Wingren
,
P.
Ellmark
,
C. A. K.
Borrebaeck
,
C. A.
Mirkin
,
H.
Fuchs
, and
S.
Lenhert
,
Small
4
,
1785
(
2008
).
15.
K.
Salaita
,
Y.
Wang
, and
C. A.
Mirkin
,
Nat. Nanotech.
2
,
145
(
2007
).
16.
B.
Basnar
and
I.
Willner
,
Small
5
,
28
(
2009
).
17.
E.
Bellido
,
R.
de Miguel
,
D.
Ruiz-Molina
,
A.
Lostao
, and
D.
Maspoch
,
Adv. Mater.
22
,
352
(
2010
).
18.
M.
Uchida
,
S.
Kang
,
C.
Reichhardt
,
K.
Harlen
, and
T.
Douglas
,
Biochim. Biophys. Acta
1800
(
8
),
834
(
2010
).
19.
E.
Bellido
,
R.
de Miguel
,
J.
Sesé
,
D.
Ruiz-Molina
,
A.
Lostao
, and
D.
Maspoch
,
Scanning
32
,
35
(
2010
).
20.
See supplementary material at http://dx.doi.org/10.1063/1.3609859 for a detailed description of the calculation of the SQUID-sample flux coupling factor and the sample characterization.
21.
M. J.
Martínez-Pérez
,
J.
Sesé
,
F.
Luis
,
D.
Drung
, and
T.
Schurig
,
Rev. Sci. Instrum.
81
,
016108
(
2010
).
22.
M. J.
Martínez-Pérez
,
J.
Sesé
,
F.
Luis
,
R.
Córdoba
,
D.
Drung
,
T.
Schurig
,
E.
Bellido
,
R.
de Miguel
,
C.
Gómez-Moreno
,
A.
Lostao
, and
D.
Ruiz-Molina
,
IEEE Trans. Appl. Supercond.
21
,
345
(
2011
).
23.
L.
Néel
,
Ann. Geophys.
5
,
99
(
1949
).
24.
W. F.
Brown
,
Phys. Rev. B
130
,
1677
(
1963
).
25.
A.
Imamoglu
,
Phys. Rev. Lett.
102
,
083602
(
2009
).

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