Mesoscopic transport in thin films of La0.67Sr0.33MnO3

• We study transport properties of La0.7Sr0.3MnO3 thin films on SrTiO3.
• Films thinner than 15 nm show a strongly non-linear behavior for 300 nm bridges.
• Non-linearities are not visible for 1 μm bridges for the same thickness.
• We infer that local removal of oxygen from bridges causes this non-linearity.

We investigate thin films of La0.7Sr0.3MnO3 grown on SrTiO3 in which bridges of 100 μm long and 1 μm or 300 nm wide (distance between voltage contacts was 25 μm) were defined lithographically. In bridges of 1 μm, we find the current–voltage characteristics to be perfectly linear (ohmic) over the full temperature range between 400 K and 10 K. Strong non-linearities however are observed for a 300 nm wide bridge in the temperature regime below the transition temperature. The non-linearities are present even when applying a high magnetic field of 9 T.