Characterization of Electrodeposited Thin Films Created for Giant Magnetoresistance
Dr. Jennifer Hampton, Hope College
The phenomenon of giant magnetoresistance (GMR) occurs when a non-magnetic thin film is sandwiched between two magnetic films. In the presence of an external magnetic field, the magnetic films align, allowing increased current flow. Electrodeposition was used to create these films necessary for GMR. The magnetic films were composed of nickel and iron while the non-magnetic films were composed of copper. These films were deposited from sulfate solutions containing nickel (100mM), iron (10mM), and copper (1mM or 2mM) onto uniformly gold-plated silicon wafers. Scanning Electron Microscopy (SEM) and simultaneous Particle Induced X-ray Emission (PIXE) and proton Rutherford Back Scattering (RBS) were used to study how the deposition time (6 or 60 minutes), deposition potential (-500mV to -1200mV vs. Ag/AgCl), and copper concentration (1mM or 2mM) affect the composition and surface structure of the deposits. The composition of samples deposited from solutions containing 1mM copper and 2mM copper were compared. The variability in each sample and between samples was also studied. The amount of deposited material was measured in three different ways: amount of charge deposited, ratio of deposit counts to gold counts found using PIXE, and layer thicknesses found using proton RBS. The three ways were found to be consistent measures of thickness.
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This material is based upon work supported by the National Science Foundation under NSF-REU Grant No. PHY/DMR-1004811 and Grant No. PHY-0969058 and the Hope College Dean for the Natural and Applied Sciences Office.