7 Tesla SQUID Magnetometer
(NSF DMR-9900855)
The Result of the Month
(February 2003)
Photoinduced Magnetic thin Film
J.-H. Park*, E. Cizmar*, M. W. Meisel*, Y.D. Huh**, D. R. Talham**
* Department of Physics, University of Florida
** Department of Chemistry, University of Florida
(a)
2.5
M (10 emu G)
off
off
off
4.0
Red LED on
-5
2.0
1.5
3.8
Blue LED on
-4
M (10 emu G)
4.2
(b)
3.6
20
1.0
22
24
26
28
30
Time (hrs)
0.5
Photoinduced M
Nonilluminated M
Light on
0.0
0
1
2
Time (hrs)
3
10
20
30
40
50
T(K)
Fig. 1 (a) M vs. Time (at 5 K, B = 50 G) upon illumination of white
light. (b) M vs. T (at 50 G) of both photoinduced and nonilluminated
states of the film. (inset) photoinduced M in different photon sources.
Fig. 2 A thin self assembled Prussian
blue film.
We have been studying mixed-metals molecule-based magnets and this month we report photoinduced
magnetization of Co-Fe cyanide in the form of a unique thin film. A thin sample was prepared by first
templating a 2D Fe-CN-Co network at the air/water interface. This well structured 2D monolayer was
transferred onto a thin Mylar film using Langmuir-Blodgett technique and served as a template for
future depositions. Subsequent immersions of separate solutions of Rb and Co ions and of Fe(CN)6
ions completed one cycle of 2D Fe-CN-Co network with Rb ions. After white light began to
continuously illuminate the thin film, the magnetization increased more than 300 % with in 30 minutes,
see Fig. 1. Regardless of the frequency in the visible region, the resulting magnetization of the film
was activated, see the inset of Fig. 1(b). Figure 1(b) compares the magnetizations of the specimen as a
function of temperature in the photoinduced and nonilluminated states. This work is partially
supported by the ACS-PRF-36163-AC5 and the NSF DGE-0209410.
* For recent information on photoiduced magnet see, H. Tokoro, S. Ohkoshi, and K. Hashimoto, Appl. Phys. Lett. 82, 1245 (2003)
Questions or Suggestions e-mail me juhyun@phys.ufl.edu