Data storage and processing using magnetic nanowires

This thesis contains data from micromagnetic simulations that investigate new methods for data storage and processing on the nanoscale using ferromagnetic nanowires. First I consider a magnetic memory, domain wall trap memory, which could compete with a number of existing devices that are currently in widespread use. Domain wall trap memory exhibits a 90% lower coercivity over traditional MRAM designs because, instead of remagnetizing a rectangular or oval magnetic free layer by moment rotation or domain nucleation, an existing domain wall is moved along a structured nanowire to remagnetize part of the wire. I determine the fields for de-pinning, switching and expulsion of domain walls in memory cells to show that the margins between them can be sufficiently large for reliable operation. The nudged elastic band method is used to show that domain wall trap memory is thermally stable at room temperature.
The second part of the thesis examines spin waves in ferromagnetic nanostructures, particularly rectangular thin-film wires, where exchange spin waves dominate. Spin wave logic devices have been proposed as a replacement for traditional silicon-based electronic logic for a range of applications. I show that is is possible to reduce spin wave reflections with boundary conditions of increased Gilbert damping constant and investigate the effects of geometry and material parameters on spin wave propagation. I go on to examine the effects of edge notches, roughness and bends on the quality of spin waves, finding that a nanowire with periodic roughness can be considered a type of magnonic crystal, with frequency band gaps corresponding to the spin wave frequency modes. It is shown that magnetic nanowires are highly suitable for use as spin wave waveguides in spin wave logic devices.