Magnetic nanowire arrays and their temperature stability Dissertation

Magnetic nanowire arrays and their temperature stability - language ExampleThese nanowires are hexagonally ar arranged and highly ordered with wire to wire distances between 30 to degree centigrade nm, wire diameters of 5 to 250 nm and lengths up to several m depending on the preparation conditions.Ferromagnetic nanowires with diameters in the range of domain wall widths or even smaller are expected to behave as virtuoso domain particles. In the easiest case such nanowires can be construe as defect-free longsighted ellipsoids with equivalent magnetization and these re bring in model systems for the investigation of magnetic interactions because their magnetic properties are not obscured by difficult-to-control volume domains. Within such nanowires the shape anisotropy, the magneto-crystalline anisotropy and in the case of very fine nanowires (diameters about 5 nm) the submit of the surface magnetism has to be considered. Depending on the distance between the nanowires the wires can be interpreted as magnetically isolated magnetic mono-domains or, in the case of arrays in alumina, as dipolar interacting mono-domains. For the sagaciousness of the port of such arrays both theoretical and experimental investigations are essential. In the following we will scantily present experimental results which demonstrate the basic magnetic properties.... Fig- Hexagonally arranged Nanowire Arrays Ferromagnetic nanowires with diameters in the range of domain wall widths or even smaller are expected to behave as single domain particles. In the easiest case such nanowires can be interpreted as defect-free long ellipsoids with homogeneous magnetization and these represent model systems for the investigation of magnetic interactions because their magnetic properties are not obscured by difficult-to-control bulk domains. Within such nanowires the shape anisotropy, the magneto-crystalline anisotropy and in the case of very fine nanowires (diameters about 5 nm) the in fluence of the surface magnetism has to be considered. Depending on the distance between the nanowires the wires can be interpreted as magnetically isolated magnetic mono-domains or, in the case of arrays in alumina, as dipolar interacting mono-domains. For the understanding of the behavior of such arrays both theoretical and experimental investigations are essential. In the following we will just present experimental results which demonstrate the basic magnetic properties. Hysteresis loops of arrays of Co-nanowires in alumina with different diameters and roughly the same length with H parallel (II) and perpendicular () to the long wire axis. Aside from the scientific attitude such arrays of ferromagnetic nanostructures are of significant interest because of their possible application as ultrahigh-density magnetic recording media. The preparation of such systems is very cheap and fast compared to expensive and time consuming methods as microlithography and molecular beam epitaxy. In addition the diameter, interwire