Faculty Sponsor's Department(s):
The spinel structure is characterized by the formula AB2O4 and consists of a cubic close-packed array of oxide ions, with A cations occupying tetrahedral holes and B cations occupying octahedral holes. Generally, A is a divalent ion, A2+, while B is a trivalent ion, B3+. Spinels often exhibit interesting magnetic properties when site mixing or a distorted structure drives a property change. In this study, the previously less researched spinels GeCo2O4 and GeFe2O4 were synthesized to investigate their magnetism and couple each spinel's magnetic behavior to its structure. The systems were prepared by solid state reactions and their purity was confirmed by X-ray diffraction. Temperature dependence of magnetic susceptibility was measured using a superconducting quantum interference device (SQUID). Preliminary research indicated that GeCo2O4 is antiferromagnetic. The magnetic behavior of GeCo2O4 was attributed to a frustrated magnetism caused by cobalt's degeneracy, which increases the number of available ground states. In order to arrive at a single ground state, a Jahn-Teller distortion causes a structural change in GeCo2O4 that could affect its magnetic and also electric properties. Further research will investigate this possibility as well as examine the magnetism of GeFe2O4. Study of the spinels GeCo2O4 and GeFe2O4 can potentially yield new insight into their magnetic behavior.