Patterned magnetic nano-structures are under extensive research due to their interesting emergent physics and promising applications in high-density magnetic data storage, through magnetic logic to bio-magnetic functionality. Bit-patterned media is an example of such structures which is a leading candidate to reach magnetic densities which cannot be achieved by conventional magnetic media. Patterned arrays of complex heterostructures such as exchange-coupled composites are studied in this thesis as a potential for next generation of magnetic recording media. Exchange-coupled composites have shown new functionality and performance advantages in magnetic recording and bit patterned media provide unique capability to implement such architectures. Due to unique resonant properties of such structures, their possible application in spin transfer torque memory and microwave assisted switching is also studied. This dissertation is divided into seven chapters. The first chapter covers the history of magnetic recording, the need to increase magnetic storage density, and the challenges in the field. The second chapter introduces basic concepts of magnetism. The third chapter explains the fabrication methods for thin films and various lithographic techniques that were used to pattern the devices under study for this thesis. The fourth chapter introduces the exchanged coupled system with the structure of [Co/Pd] / Fe / [Co/Pd], where the thickness of Fe is varied, and presents the magnetic properties of such structures using conventional magnetometers. The fifth chapter goes beyond what is learned in the fourth chapter and utilizes polarized neutron reflectometry to study the vertical exchange coupling and reversal mechanism in patterned structures with such structure. The sixth chapter explores the dynamic properties of the patterned samples, and their reversal mechanism under microwave field. The final chapter summarizes the results and describes the prospects for future applications of these structures.

Today magnetic recording is still the leading technology for mass data storage. Its dominant role is being reinforced by the success of cloud computing, which requires storing and managing huge amounts of data on a multitude of servers. Nonetheless, the hard-disk storage industry is presently at a crossroads as the current magnetic recording techno

Novel Magnetic Nanostructures: Unique Properties and Applications reviews the synthesis, design, characterization and unique properties of emerging nanostructured magnetic materials. It discusses the most promising and relevant applications, including data storage, spintronics and biomedical applications. Properties investigated include electronic, self-assembling, multifunctional, and magnetic properties, along with magnetic phenomena. Structures range from magnetic nanoclusters, nanoparticles, and nanowires, to multilayers and self-assembling nanosystems. This book provides a better understanding of the static and dynamic magnetism in new nanostructures for important applications. - Provides an overview of the latest research on novel magnetic nanostructures, including molecular nanomagnets, metallacrown magnetic nanostructures, magnetic dendrimers, self-assembling magnetic structures, multifunctional nanostructures, and much more - Reviews the synthesis, design, characterization and detection of useful properties in new magnetic nanostructures - Highlights the most relevant applications, including spintronic, data storage and biomedical applications

Timely and comprehensive, this book presents recent advances in magnetic nanomaterials research, covering the latest developments, including the design and preparation of magnetic nanoparticles, their physical and chemical properties as well as their applications in different fields, including biomedicine, magnetic energy storage, wave-absorbing and water remediation. By allowing researchers to get to the forefront developments related to magnetic nanomaterials in various disciplines, this is invaluable reading for the nano, magnetic, energy, medical, and environmental communities.

This unique handbook compiles and details cutting-edge research in nanomagnetism and its applications in spintronics, magnetoplasmonics, and nonlinear magneto-optics. Fundamental aspects of magnetism relevant to nanodevices and new spin-transfer torque random-access memory (STT-RAM), current-induced domain wall motion memory, and spin torque oscill

Presented here are micromagnetic simulations to investigate alternative magnetic recording technologies including bit patterned media and domain wall storage. I have used a finite element/boundary element method to investigate the dynamics of the write process in magnetic recording systems; and a nudged elastic band method is used to calculate the thermal stability of written bits. Microwave assisted magnetization reversal of single phase media and exchange spring media is investigated. A reduction of the switching field by about a factor of two can be found in both single phase and exchange spring media when the microwave field reaches an amplitude that is 12 percent of the remanent coercivity without microwave assist. Furthermore, layer-selective writing of two-layer bitpatterned media is demonstrated by employing microwave assist technique. Selectivity is achieved by controlling the frequency of an oscillating magnetic field in the GHz range, applied in addition to the head field. Generation of the microwave field by means of a wire next to the tip of a single pole head is proposed. Optimization of writing heads is performed using micromagnetics and surrogate optimization. The shape of the pole tip is optimized for bit patterned, exchange spring recording media. I computed the write error rate and the adjacent track erasure for different maximum anisotropy in the multilayer, graded media. The results show a linear trade off between the error rate and the number of passes. Finally I have calculated magneto static fields from transverse and vortex magnetic domain walls in a planar Ni81Fe19 nanowire. These calculations indicate the required sensitivity of a nearby sensor for detecting either a domain wall of any type or being able to distinguish the domain wall character. Optimization of writing heads is performed using micromagnetics and surrogate optimization. The shape of the pole tip is optimized for bit patterned, exchange spring recording media. I computed the write error rate and the adjacent track erasure for different maximum anisotropy in the multilayer, graded media. The results show a linear trade off between the error rate and the number of passes. Finally I have calculated magneto static fields from transverse and vortex magnetic domain walls in a planar Ni81Fe19 nanowire. These calculations indicate the required sensitivity of a nearby sensor for detecting either a domain wall of any type or being able to distinguish the domain wall character.

The data storage industry recently substituted its five-decade-old technology (longitudinal magnetic recording), which reached its fundamental limitations due to thermal instabilities in the recording media, with perpendicular magnetic recording. Nonetheless, the lifetime of this newly adopted technology and other next generation alternatives including heat-assisted magnetic recording (HAMR) and bit patterned media (BPM) is comparably short. In order to defer the superparamagnetic limit substantially beyond 1 Tbits/in 2, it may be necessary to stack information in a third (vertical) dimension.

This book presents the latest research in ultrathin carbon-based protective overcoats for high areal density magnetic data storage systems, with a particular focus on hard disk drives (HDDs) and tape drives. These findings shed new light on how the microstructure and interfacial chemistry of these sub-20 nm overcoats can be engineered at the nanoscale regime to obtain enhanced properties for wear, thermal and corrosion protection – which are critical for such applications. Readers will also be provided with fresh experimental insights into the suitability of graphene as an atomically-thin overcoat for HDD media. The easy readability of this book will appeal to a wide audience, ranging from non-specialists with a general interest in the field to scientists and industry professionals directly involved in thin film and coatings research.