Temperature dependence of magnetic
anisotropy of nanocrystalline
0.90(Fe O )/0.10(ZnO) studied by
2
3
FMR
1,2
1
2
2
3
N. Guskos , S. Glenis , G. Zolnierkiewicz , J. Typek , D. Sibera ,
3
and U. Narkiewicz
1
Solid State Section, Department of Physics, University of Athens, Panepistimiopolis, 15 784, Greece;
2
Institute of Physics, West Pomeranian University of Technology, Al. Piastow 48, 70-311 Szczecin, Poland;
3
Institute of Chemical and Environmental Engineering, West Pomeranian University of Technology,
Al. Piastow 17, 70-310 Szczecin, Poland.
The nanocrystalline 0.90(Fe O )/0.10(ZnO) sample has been prepared by coprecipitation and calcination method. The phase composition of 2 3
sample was determined by X-ray diffraction. It is dominated by Fe O and ZnO phases and also a very small concentration of ZnFe O phase was 2 3 2 4
identified. The ferromagnetic resonance (FMR) investigation of 0.90(Fe O )/0.10(ZnO) nanopowder has been carried out in the temperature range 2 3
from liquid helium to room temperature (Fig.1). The asymmetrical and very intense magnetic resonance line was recorded at all temperatures.
A significant shift of the FMR spectra towards low magnetic fields with decreasing temperature was observed. A very good fitting by two Lorentzian functions has been achieved which suggests the existence of a strong anisotropic magnetic interaction. The decomposition of the FMR
spectrum of 0.90(Fe O )/0.10(ZnO) registered at 90 K on two components is shown in Fig. 2. Temperature dependence of the resonance fields (left 2 3
panel), linewidths (middle panel) and FMR signal amplitudes (right panel) for two component lines of the 0.90(Fe O )/0.10(ZnO) sample is 2 3 presented in Fig. 3. Certain similarities can be observed in temperature dependence of the FMR parameters registered previously for
0.95(Fe O )/0.05(ZnO) sample but the measured values are essentially different. The temperature shift of resonance field ÄH /ÄT, the broadening of 2 3 r
the resonance line as well as FMR signal amplitude change more strongly with temperature in comparison to 0.95(Fe O )/0.05(ZnO) nanopowder. 2 3
The following values of ÄH /ÄT gradient were obtained for 0.90(Fe O )/0.10(ZnO) sample : 16.7(1) Gs/K and 20.7(1) Gs/K for temperature above r 2 3
60 K (for 0.95(Fe O )/0.05(ZnO) it was 3.7(1) Gs/K and 8.3(1) Gs/K [1]) while below 40 K the values were 41.5(1) Gs/K and 56.0 (1) Gs/K (in contrast 2 3
to 40.5 Gs/K and 49.6 Gs/K for 0.95(Fe O )/0.05(ZnO)). Thus the reorientation processes are more intense in 0.90(Fe O )/0.10(ZnO) sample, 2 3 2 3 especially at high temperature.
Acknowledgements
Publication of this paper was realised with partial financial support from the budget resources of the West Pomeranian Voivodeship.
1 0 0 0 2 0 0 0 3 0 0 0 4 0 0 0 5 0 0 0 6 0 0 0 -8 0 0 0 0 -6 0 0 0 0 -4 0 0 0 0 -2 0 0 0 0 0 2 0 0 0 0 4 0 0 0 0 6 0 0 0 0 d c "/ dH [A rb .u ni ts ] M a g n e tic fie ld H [G s ] 4 .1 K 2 9 5 K 0 1 0 0 0 2 0 0 0 3 0 0 0 4 0 0 0 5 0 0 0 6 0 0 0 7 0 0 0 -6 0 0 0 0 -4 0 0 0 0 -2 0 0 0 0 0 2 0 0 0 0 4 0 0 0 0 d c "/ dH [A rb .u ni ts ] M a g n e tic fie ld H [G s ] 9 0 K 9 0 % F e L in e 1 L in e 2 E x p e rim e n ta l F ittin g 0 20 40 60 80 100 120 140 160 500 1000 1500 2000 2500 3000 H(1) H(2) R e s o n a n c e fi e ld H r [G s ] Temperature T [K] 0 20 40 60 80 100 120 140 160 500 600 700 800 900 1000 1100 dH1 dH2 L in e w id th D H [G s ] Temperature T [K] 0 20 40 60 80 100 120 140 160 10000 15000 20000 25000 30000 35000 40000 45000 50000 55000 Amp1 Amp2 A m p lit u d e A [a rb . u n it s ] X Axis Title
Fig. 1. Registered FMR spectra of 0.90(Fe O )/0.10(ZnO) at different temperatures.2 3 Fig. 2. Decomposition of the FMR spectrum of 0.90(Fe O )/0.10(ZnO) registered at 90 K.2 3
