Nanomagnetism in Hydrothermal Ferrites Probed by Mfm
نویسنده
چکیده
Nanomagnetic structures of hydrothermal NiZn ferrites sintered at various temperatures was studied in this work through Magnetic Force Microscopy (MFM) using different magnetically characterized tips. The magnetic patterns varied according to the tip employed and were correlated to the magnetic induced field generated by these different coated tips. NiZn ferrites were produced at 200°C by hydrothermal synthesis and sintered at temperatures ranging from 1100°C to 1400°C. Ceramic bodies were obtained with final grain sizes between 3 and 30 μm, porosities of 8-3%, and composition Ni0.34Zn0.60Fe2.06O4 [1]. A commercial MFM from Digital Instruments was employed to study the magnetic features of the samples. Topographic contribution to the magnetic image was eliminated by using two interleaved scans, and both the topographic and the magnetic image could be storage simultaneously. The signal from the mechanically modulated cantilever was analyzed in a lock-in amplifier and the phase shift, proportional to the force gradient, is recorded. Magnetic coated tips were employed in frequency mode for the magnetic characterization: (i) low-coercivity-LC (Fe-based coating); (ii) low-moment-LM (15 nm-thick Co alloy coated); and (iii) high-coercivity-HC (Co alloy coated) tips with resonant frequencies in the range 60-100 kHz, spring constant of 1-5 N/m, and cantilever length of 225 μm.
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