Magnetic-field-dependent carrier injection at La2/3Sr1/3MnO3/ and organic semiconductors interfaces

We have fabricated organic diodes utilizing several ∏-conjugated organic semiconductors (OSEC) as spacer layers between La2=3Sr1=3MnO3 (LSMO) and various metallic electrodes, and measured their magnetoresistance (MR) and magnetoelectroluminescence (MEL) responses. The devices exhibit large negative high-field MR responses that resemble the MR response of the LSMO electrode, but amplified by ~3 orders in the resistance, and accompanied by a positive high-field MEL effect. These magnetic-field effects result from enhanced carrier injection at the LSMO-OSEC interface that is attributed to the anomalous field-dependent Fermi level shift in LSMO.