Magnetoresistance and its relaxation of nanostructured La-Sr-Mn-Co-O films: Application for low temperature magnetic sensors

The results of magnetoresistance (MR) and resistance relaxation of nanostructured La1-xSrx(Mn1-yCoy)(z)O-3 (LCMCO) films doped with different Co amount (Co/(La + Sr) = 0.06; 0.12; 0.14) while keeping constant Sr (x = 0.2) deposited by Pulsed Injection MOCVD technique, are presented and compared with the reference manganite La(0.8)Sr(0.2)MnzO(3) (LSMO) film. The MR was investigated in pulsed magnetic fields up to 25 T in the temperature range 4-200 K while the relaxation processes were studied in pulsed fields up to 10 T and temperatures in the range of 100-300 K. It was demonstrated that at low temperatures the MR(%) and sensitivity S(mV/T) of Codoped films have significantly higher values in comparison with the LSMO ones, and increases with increase of Co/(La + Sr) ratio. The observed temperature-insensitive MR in the range of 4-200 K suggests possibility to use these films for sensors applications. The magnetic memory effects were investigated as resistance relaxation processes after the switch-off of the magnetic field pulse. The observed 'fast' (similar to 300 mu s) resistance relaxation was analyzed by using the Kolmogorov-Avrami-Fatuzzo model, taking into account the reorientation of magnetic domains into their equilibrium state, while the 'slow' process (>ms) was explained by using the Kohlrausch-Williams-Watts model considering the interaction of the magnetic moments in disordered grain boundaries. It was concluded that Co-doped nanostructured manganite LSMCO films having a higher sensitivity and lower memory effects in comparison with the LSMO films could be used for the development of pulsed magnetic field sensors operating at low temperatures.

Automated summary

The study found that Co-doped LCMCO films exhibit higher values of MR and sensitivity at low temperatures, showing potential for sensor applications. Different models were proposed to explain the resistance relaxation processes observed, providing insights into the mechanisms behind the relaxation phenomena in these films.