The passage of spin-polarized currents through magnetic nanocontacts can lead to the excitation of self-sustained
vortex oscillations in the free layer of a spin-valve stack. These oscillations involve the large amplitude translational
motion of the vortex core about the contact region, with oscillation frequencies typically in the 200-500
MHz range. Here, we present a detailed experimental study of such current-driven vortex oscillations. In particular,
we show that the oscillation mode is possible in zero applied magnetic field and is only stable within a
range of in-plane applied fields.
We aim to explore the nanostructuring potential of a highly focused pencil of ions. We show that focused ion beam technology (FIB) is capable of overcoming some basic limitations of current nanofabrication techniques and allowing innovative patterning schemes for nanoscience. In this work, we first detail the very high resolution FIB instrument developed specifically to meet nanofabrication requirements. Then we introduce and illustrate some new patterning schemes for next-generation FIB processing. These patterning schemes are: 1. nanoengraving of membranes as a template for nanopores and nanomask fabrication; 2. local defect injection for magnetic thin film direct patterning; 3. function of graphite substrates to prepare 2-D organized arrays of clusters; and 5. selective epitaxy of III-V semiconductors on FIB patterned surfaces. Finally, we show that FIB patterning allows "bottom-up" or "organization" processes.