NANOSTRUCTURE OF GIANT MAGNETORESISTIVE OXIDE FILM ND2 3SR1/3MNO3 BY SCANNING-TUNNELING-MICROSCOPY/

Scanning tunneling microscopy was used to study the surface nanostruct ure of the epitaxial him Nd2/3Sr1/3MnO3 that shows giant magnetoresist ance. The surface morphology of the film consists of a number of overl apping platelets of about 30-35 Angstrom diameter that grow at an angl e of 35 degrees-45 degrees to the surface normal. The peak to peak hei ght of the platelets are multiples of the c-axis lattice parameter of 7.85 Angstrom showing that the growth of the platelets takes place by the layer by layer addition of one formula unit. The mean surface roug hness is about 10 Angstrom. In the range of a few microns the film exh ibits no defects or dislocations. The film is unstable in ambient atmo sphere and tends to get covered by an adsorbate layer. Tip-surface int eractions cause the adsorbate to be dislodged exposing the surface nan ostructure. The degradation of the film in real time when imaged in ai r was recorded. The adsorbates increase the surface roughness of the f ilm.