Electrical & Computer Engineering, Department of


Date of this Version

Fall 12-2011


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Electrical Engineering, Under the Supervision of Professors Eva Schubert and Mathias Schubert. Lincoln, Nebraska: December 2011

Copyright 2011 Dan Liang


In this thesis, dielectric polymer and magnetic nanoparticles were utilized to hybridize FeNi Slanted columnar thin films (SCTFs). Firstly Fe3O4 in PMMA matrix was prepared by physical blending process. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to investigate the dispersion of the nanoparticles in PMMA matrix and the preparation conditions were varied to optimize the dispersion. The hybridized materials were prepared by the infiltration of PMMA and 5 wt% Fe3O4 nanoparticles/PMMA to the voids of FeNi SCTFs. Spin-coating and annealing process were employed to reach an excellent infiltration.

The structural property of FeNi SCTFs and FeNi SCTF composites (FeNi SCTFs after infiltration) was studied by GE and SEM. The anisotropic Bruggeman effective medium approximation (AB-EMA) was used to model the experimental data. The GE analysis successfully characterized the structural parameters of the samples and the results show the structure of nanocolumns was changed due to the infiltration. SEM result confirmed the structural property found by GE. The GE analysis also revealed a strongly anisotropic optical property of the samples. The optical constants along the three major axes of the biaxial layer can be obtained by modeling. Due to the excellent material infiltration into the void of SCTFs, the optical constants along the three major axes have enhanced greatly across the investigated spectral range.

The magnetic property of the samples was characterized by Alternating field gradient magnetometer (AGFM) and MOGE. The hysteresis loops measured by AGFM in different configuration reflected the anisotropic nature of the magnetization within the samples. The MOKE of the samples was measured in polar configuration and the corresponding complex MO tensor element was determined in the spectral range. Vector magneto-optical generalized ellipsometry (VMOGE) with the external magnetic field rotating along different loops was utilized to measure the SCTF composites. The three complex magneto-optical tensor elements were determined by the loop measurements to study the effect of the nanoparticles on the MO property of FeNi SCTFs.

Advisor: Eva Schubert and Mathias Schubert