Influence of the electronic structure on the differential conductance in manganite tunnel junctions

Abstract We report on the nature of the tunneling transport across break junctions based on the La 0.7 Sr 0.3 MnO 3 manganite by examining the scaling behavior of the differential conductance d I /d V as a function of the bias voltage V . The obtained d I /d V vs. V curves, which are proportional to the density of states N ( E ) for a single electron tunneling, were compared with the electronic structure of the La 0.7 Sr 0.3 MnO 3 perovskite. It appeared that characteristic slope changes of the d I /d V − V characteristics at 0.8 eV were probably connected with the energy difference between the O-2p and Mn-e g ↑ bands. The slopes at 1.5 and 3 V coincided with the typical values of the t 2g ↑−e g ↑ and e g ↑−t 2g ↓ separations of Mn ions in an octahedral coordination. An inflection at 4 V is in a good agreement with the O–2p→t 2g ↓ excitation.