Low-frequency $1∕f$-noise in $(La0.7Sr0.3MnO3)0.95:(MgO)0.05$ nanocomposite films

The $(La0.7Sr0.3MnO3)0.95:(MgO)0.05$ nanocomposite system (LSMO:MgO) shows a low-field magnetoresistance up to 30% at low temperatures. The low-frequency $1∕f$-noise was investigated extensively to characterize the $LSMO∕MgO$ interface. The noise was found to be independent of both an applied magnetic field and the bias current. Furthermore, the temperature dependence of the noise level shows a maximum which can be connected to the temperature dependence of the resistance. The measured noise level is comparable to epitaxial manganite systems without doped grain boundaries. This suggests that the quality of the coherent $LSMO∕MgO$ interfaces where the low-frequency noise is predominantly generated is very high.