Scanning Tunneling Spectroscopy on Pr_(0.68)Pb_(0.32)MnO_(3) Single Crystals

摘要

Scanning tunneling microscopy/spectroscopy studies were carried out on single crystals of colossal magnetoresistive manganitePr_(0.68)Pb_(0.32)MnO_(3) at different temperatures in order to probe their spatial homogeneity across the metal-insulator transition temperature T_(M-I)(approx255 K). A metallic behavior of the local conductance was observed for temperatures T < T_(M-I). Zero bias conductance (dI/dV)_(v(velence)0), which is directly proportional to the local surface density of states at the Fermi level, shows a single distribution at temperatures T < 200 K suggesting a homogeneous electronic phase at low temperatures. In a narrow temperature window of 200 K < T < T_(M-I), however, an inhomogeneous distribution of (dI/dV)_(v(velence)0) has been observed. This result gives evidence for phase separation in the transition region in this compound.