Magnetoresistance in nanoparticles /by Mohammad Faheem.

The objective of this research was to develop an atomistic, first principles-based approach for the study of dilute magnetic semiconductor (DMS) materials at the nano scale, focusing on the goal of predicting the extent of magnetoresistance. DMS materials are those semiconductors that exhibit magnetoresistance and other desirable magnetic properties. DMS candidates that were studied in this work included Co doped Cu{esc}b2{esc}sO, Co doped ZnO and Ni doped ZnO. The method used was to adapt Density Functional Theory and Non Equilibrium Green's Function formalism (DFT-NEGF). This was a new approach currently being developed to study conventional transistor materials, and this approach has been successfully modified to allow application to DMS materials. The results were a computational observation of magnetoresistance. This included a prediction of 3.8% increase in magnetoresistance due to Co-doping of Cu{esc}b2{esc}sO, and this was pleasingly close to an experimentally observed increase of 5%. The results also included the prediction of still others such as Ni-doped ZnO and Co-doped ZnO. The conclusion was that our innovation with the DFT-NEGF formalism makes possible the computational screening for magnetoresistance. The benefits included the potential for the discovery of more unique DMS materials for the spintronics industry other new applications.Thesis (Ph. D., Material Sciences and Engineering)--University of Idaho, January 2008