Magneto-Electroluminescence Study of Fringe Field in "Magnetic" Organic Light-Emitting Diodes.

Magneto-electroluminescence (MEL) represents the electroluminescence intensity change upon application of an external magnetic field. We show that the MEL field response in "magnetic" organic light-emitting diodes, where one electrode is ferromagnetic (FM), is a powerful technique for measuring the induced fringe field, , from the FM electrode in the organic layer. We found that the in-plane fringe field, , from 3 nm Co and NiFe FM electrodes is proportional to the applied field, . The fringe field of the 3 nm NiFe film was also investigated for an applied out-of-plane magnetic field, . We found that the out-of-plane fringe field has two components: a component that is parallel or antiparallel to and remains unchanged with the distance, , from the FM electrode and the other component that is highly inhomogeneous, parallel to the surface, and steeply decreases with . We show that the obtained is independent of the underlying mechanism for the MEL() response and thus may be considered universal.