AVS 50th International Symposium
    Magnetic Interfaces and Nanostructures Wednesday Sessions
       Session MI-WeP

Paper MI-WeP13
Increase of Conductance and Magnetoconductance with Oxygen Exposure During Deposition of Spinvalves

Wednesday, November 5, 2003, 11:00 am, Room Hall A-C

Session: Poster Session
Presenter: A.T. McCallum, National Institute of Standards and Technology
Authors: A.T. McCallum, National Institute of Standards and Technology
S.E. Russek, National Institute of Standards and Technology
Correspondent: Click to Email
It has been found that the magnetoconductance and conductance of spinvalves increase when a small partial pressure of oxygen( 1 x 10@super -9@ - 5 x 10@super -9@ torr)is present during deposition. Conductance measurements made during the sputter deposition of spin valves show directly that the conductance increases are occurring in the active layers of the spin valve flims. The Ne`el coupling between the free layer and the pinned layer is also reduced suggesting that the oxygen is leading to smoother growth. Eventually a high enough partial pressure of oxygen will lead to oxidation of the deposited metal and a drop in giant magnetoresistance. A series of conductance measurements at different gas flows show the onset of oxidation beginning with the NiFe and Cu layers. Relatively thick layers of material also have a higher conductance when grown in the presence of oxygen. The in-situ conductance measurement for NiFe layers reveal that the increase in conductance is starts at 1 nm and ends at 5 nm. After this the differential conductivity is the same for samples grown with and without oxygen. This is consistent with the samples grown in oxygen having a smoother surface but essentially the same microstructure.