Studies of Nanoconstrictions, Nanowires and Fe3O4 Thin Films

This work examines electrical and magnetic properties in nanometric materials with a range of scales: atomic-sized nanoconstrictions, micro- and nanowires and thin films. It describes an approach to tailoring magnetic and other properties of nanostructures.

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This work constitutes a detailed study of electrical and magnetic properties in nanometric materials with a range of scales: atomic-sized nanoconstrictions, micro- and nanowires and thin films. Firstly, a novel method of fabricating atomic-sized constrictions in metals is presented; it relies on measuring the conduction of the device while a focused-ion-beam etching process is in progress. Secondly, it describes wires created by a very promising nanolithography technique: Focused electron/ion-beam-induced deposition. Three different gas precursors were used: (CH3)3Pt(CpCH3), W(CO)6 and Co2(CO)8. The thesis reports the results obtained for various physical phenomena: the metal-insulator transition, superconducting and magnetic properties, respectively. Finally, the detailed magnetotransport properties in epitaxial Fe3O4 thin films grown on MgO (001) are presented. Overall, the new approaches developed in this thesis have great potential for supporting novel technologies.