Study of the magnetic-Alq3 interface in organic spin-valves

The interface between the organic semiconductor tris(8-hydrixyquinolate) aluminium (Alq3) and two different magnetic electrodes has been investigated using X-ray photoelectron spectroscopy (XPS), Kelvin Probe, atomic force microscopy (AFM) and magneto-optic Kerr effect (MOKE) magnetometry. The transition metal magnetic electrode/Alq3 films were first measured using a XPS, and then washed and remeasured. It was found that Alq3 still existed on the magnetic electrode after washing. This suggests that the Alq3 chemisorbs onto the transition metal electrode surfaces. Using MOKE magnetometry, the surface magnetisation of the transition metal electrodes was studied. It was found that the surface magnetisation of the NiFe electrode changed with the Alq3 layer on top, which was taken to be due to the Alq3 chemisorption onto the NiFe electrode, so changing the electronic states at the interface. © 2014 Elsevier B.V. All rights reserved.