Hope College Physics Department Research Experiences for Undergraduates Summer 2009 Project Summary

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) onto gold-plated silicon wafers. Particle induced x-ray emission (PIXE) and atomic force microscopy (AFM) were used to study how the deposition time (either 6 or 60 minutes) and deposition potential (ranging from -500mV to -1200mV vs. Ag/AgCl) affect the composition and surface roughness of the deposits. PIXE analysis showed that, at less negative potentials, the deposit is dominated by copper, and as the potential becomes more negative, the deposit has a greater nickel and iron concentration. PIXE also revealed that the ratio of iron to total magnetic material changes with varying potential and reaches a maximum value at -900mV. Analysis of RMS roughness from the AFM data for varying length scales reveals the fractal nature of the deposits below a characteristic length.

__________________________________________________________________________________________________________________________________________________________
Publications and Presentations:
“Analysis of Electrodeposited Nickel-Iron Alloy Film Composition Using Particle-Induced X-ray Emission”, Alyssa A. Frey*, Nicholas R. Wozniak*, Timothy B. Nagi*, Matthew P. Keller*, J. Mark Lunderberg*, Graham F. Peaslee, Paul A. DeYoung, and Jennifer R. Hampton. Int. J. Electrochem, IJELC/604395, (2011).
"Electrodeposition and Characterization of Thin Films Created for Giant Magnetoresistance", Alyssa Frey, Nicholas Wozniak, and Jennifer Hampton, contributed poster, American Physical Society April Meeting 2010, Washington, DC, (February 14, 2010).
“An Electrochemical Cell for the Efficient Turn Around of Wafer Working Electrodes", Nicholas R. Wozniak, Alyssa A. Frey, Lucas W. Osterbur, Timothy S. Boman, and Jennifer R. Hampton,submitted to Rev. Sci. Instrum.
“Electrodeposition and Characterization of Thin Films Created for Giant Magnetoresistance", Alyssa A. Frey, Senior Seminar Presentation, University of Wisconsin-Eau Claire, Eau Claire, WI (December 3, 2009).
“Electrodeposition and Characterization of Thin Films Created for Giant Magnetoresistance", Alyssa A. Frey, Nicholas R. Wozniak, and Jennifer R. Hampton, contributed poster, Science and Engineering Summer Undergraduate Research Symposium, Notre Dame University, Notre Dame, IN, (July 31, 2009).

.