Electrodeposited magnetite with large magnetoresistive response at room temperature and low magnetic fields
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Iron oxide layers were obtained by electrodeposition method on Cu substrates. The electrolyte containing Fe2(SO4)3, NaOH, and Triethanolamine was stirred at a temperature of 65 °C and the depositions were performed potentiostatically in a conventional three electrode cell at a potential of −1.1 V vs SCE. Parallel magnetoresistance values of −6.2% at 3 kOe were obtained for measurements at room temperature. The magnetoresistive curves showed reduced hysteresis loop, temporal stability, and no saturation for the maximum applied magnetic field. Our results show that for the case of the granular magnetite that we grow, the AMR has opposite sign of that of 3d magnetic alloys. Allied to high values of resistivity, these properties are potentially adequate for the development of magnetic devices such as field sensors. Additional characterization was obtained by using scanning electron microscopy and vibrating sample magnetometry.
The present research was supported by FAPESC, CNPQ and CAPES (Brazil), CICyT (Spain) and MUNDIS project (EC). The authors wish to thank M. F. Alamini and D. Aragão for helping with the preparation of the electrodeposited layers at the LFFS/UFSC. RGD is currently receiving a post-doc stipend from CNPQ. JSC present address is Facultad de Quimica/Materiales, Universidad Autónoma de Querétaro, México.
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