All these techniques can be used for modern application for example in telecommunications and data storage systems. Several measurement techniques which have been used to characterise magnetization dynamics such as femtosecond spectroscopy, pulse inductive microwave magnetometer, FMR force microscopy, network analyzer FMR and high-frequency electrical measurements of magnetodynamics. It also yields direct information about the uniform precession mode of the nanowires which can be related to the average anisotropy magnitude. The dynamic properties of magnetic materials can be easily perturbed by ferromagnetic resonance (FMR), as they can excite standing spin waves due to magnetic pinning. It has been applied to a range of materials from bulk ferromagnetic materials to nano-scale magnetic thin films and now a day’s people have started research to characterise nanoparticles and nanowires systems. They exhibit ferromagnetic resonance (FMR) even at zero bias fields and, due to their high saturation magnetization, operating frequency can be tuned with DC fields.įMR is a useful technique in the measurement of magnetic properties of ferromagnetic materials. Since they have high aspect ratio, electromagnetic waves can easily penetrate through them. The ferromagnetic nanowires in anodic alumina (AAO) templates seem to be attractive substrates for microwave applications. The most important parameters that control dynamic behaviors are the internal fields and damping constant. Recently, due to the development of spintronics, there have been increasing interests in the microwave dynamics of one-dimensional structures such as nanowires and two dimensional structures like multilayer magnetic films. In addition, experimental approach to synthesis such structures and detecting material properties using various techniques will be discussed in brief. State-of-the-art calculations for resonance frequency in ferromagnetic nanowires (solid and hollow) and multilayer nanowires are presented. This chapter begins with a brief overview of the historical development of the theory of ferromagnetic resonance in magnetic nanostructures. Furthermore, microwave devices, such as circulators or filters for wireless communication and automotive systems can be fabricated on ferromagnetic nanowires embedded in AAO substrates.
Their potential applications might be explored in spintronic devices and more specifically in magnetic random access memory (MRAM) and magnetic logic devices. The fabrication of such nanowires in polycarbonate track-etched and anodic alumina membranes have been widely studied during the last 15 years. Ferromagnetic nanowires showed solitary and tunable magnetization properties due to their inherent shape anisotropy.
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