M. El-Hilo, A.A. Dakhel / Journal of Magnetism and Magnetic Materials 323 (2011) 2202–2205
2205
Accordingly, the observed RT FM behavior in the samples examined
is consistent with a bound magnetic polaron (BMP) model.
0.012
0.006
0
0.0012
0.0006
0
4. Conclusions
By thermal co-dissociation of Zn and Mn acetylacetonates, a
powder of ZnO:Mn was synthesized using two routes: (I)
co-dissociation in open environmental conditions and (II)
co-dissociation in a closed atmosphere. Samples with Mn con-
tents of 3.9% (I), 3.3% (II) and 4.2% (II) were examined. The sample
prepared in an open atmospheric environment exhibited pure
paramagnetic behavior, whereas the samples prepared in a closed
environment exhibited both paramagnetic and ferromagnetic
behavior. Magnetic analysis showed that the magnetic moment
per dopant ions for the samples examined were in the range of
-0.006
-0.012
-0.0006
-0.0012
Mn 3.3% (II)
Mn 4.2% (II)
-2000
-1000
0
1000
2000
Applied Field H (Oe)
Fig. 4. Measured room temperature magnetization curves for the samples
prepared in a closed environment, 3.3% (II) Mn and 4.2% (II) Mn, after removing
the paramagnetic component.
4.2–6 mB/Mn. The percentages of coupled Mn atoms to the total
Mn atoms were found to be extremely small (less than 0.1%),
which by itself cannot explain the observed RT hysteresis loops.
Thus, the FM coupling between coupled Mn ions has to be
mediated via defects in order to give rise to long-range ferromag-
netic order. The observed RT FM in this study is attributed to the
preparation conditions, since samples prepared in a closed envir-
onment may suffer from oxygen deficiency, i.e. may have higher
oxygen vacancies. With such low Mn contents, the observed room
temperature ferromagnetic order supports the bound magnetic
polarons (BMP) model.
Table 2
Paramagnetic susceptibility, saturation magnetization, number of Mn atoms,
estimated magnetic moment per dopant atom, and the percentage of NFM/NMn
for the samples examined.
Sample wp (emu/gOe) Ms (emu/g) NMn/g
m/Mn atom NFM/NMn (%)
3.9% (I) 4.64 ꢃ 10ꢀ6
3.3% (II) 3.58 ꢃ 10ꢀ6
4.2% (II) 9.36 ꢃ 10ꢀ6
–
3.42 ꢃ 1020 4.4 mB
2.88 ꢃ 1020 4.2 mB
3.63 ꢃ 1020 6.1 mB
–
0.00123
0.015
0.011
0.073
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m
ð2Þ
is the
m
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