Potentiometric imaging of (La0.7Sr0.3)MnO3 thin films

Scanning tunneling potentiometry has been used to simultaneously image the surface topography and map the potential distribution on films of (La0.7Sr0.3)MnO3 deposited on polycrystalline and single crystal MgO substrates. Potential steps in the polycrystalline films coincide with the crystallite boundaries in the film. The grain boundary resistivity varies in the range 3×10−7–3×10−5 Ω cm2, with a typical value of 6×10−6 Ω cm2.