Heterostructures consist of combinations of different materials, which are in contact through at least one interface. Magnetic heterostructures combine different physical properties which do not exist in nature. This book provides the first comprehensive overview of an exciting and fast developing field of research, which has already resulted in numerous applications and is the basis for future spintronic devices.

Investigating the damping processes and the behavior of dynamic magnetic properties in ferromagnetic thin films has been an important key towards design and fabrication of different microwave and magnetic recording devices. This thesis discusses the dynamic magnetic properties and also the physics behind different relaxation mechanisms in ferromagnetic thin films using comprehensive experimental investigations by means of broadband ferromagnetic resonance (FMR) technique. In chapter one the basics of ferromagnetic resonance technique and the experimental features of the FMR setup used in this study are discussed, also the FMR data analysis is explained. Chapter two is devoted to the study of the interfacial perpendicular magnetic anisotropy (PMA) and damping parameter in Co2FeAl thin films. In chapter three broadband temperature dependent FMR measurements were carried out on Ni80Fe20/Gd thin films to investigate the behavior of ferromagnetic relaxation, and gyromagnetic ratio as the system goes through the Curie temperature of Gd. In chapter four, the ferromagnetic relaxation mechanisms in ferrites are discussed. The low loss Nikel Ferrite and Lithium ferrite single crystal, thin and ultra-thin films were characterized by detailed FMR measurements to investigate the effect of microstructural defects on the magnetization relaxation. A comprehensive study on the interlayer exchange coupling strength in Co90Fe10/Ru/ Co90Fe10 multilayers is the subject of chapter five, in which the mutual spin pumping is discussed as a recently discovered channel for relaxation in exchange coupled multilayers.

This thesis presents recent developments in magnetic coupling phenomena of ferrimagnetic rare-earth transition-metal Tb-Fe alloys and coupled systems consisting of ferri-/ferromagnetic heterostructures. Taking advantage of the tunability of the exchange coupling between ferrimagnetic and ferromagnetic layers by means of stoichiometry of the Tb-Fe layer, the variable number of repetitions in the Co/Pt multilayer as well as the thickness of an interlayer spacer, it is demonstrated that large perpendicular unidirectional anisotropy can be induced at room temperature. This robust perpendicular exchange bias at room temperature opens up a path towards applications in spintronics.

In hybrid organic spintronic devices, the active regions are essentially the hybrid interfaces. The first part of this thesis shows that molecular exchange bias in Co/MTPP and Co/CoPc systems is not an interface effect but originates from air-driven oxidation of the Co films. The second part introduces a new Ferromagnetic Nuclear Resonance methodology which showed that 15 monolayers of ZnTPP are required to obtain heterostructures with continuous molecular films and that their morphology depends on the nature of the underlayer (Co or Fe). In addition, the interfaces are asymmetrical with sharp Co/ZnTPP interface and rough ZnTPP/Co interface. These analyses have been confirmed by TEM. Moreover, FNR showed that no interfacial magnetic hardening effect exists in these systems. This is consistent with the fact that the Co/ZnTPP interfaces are governed by weak van der Waals interactions and that no signature of strong chemical bonds between interfacial ZnTPP molecules and Co atoms has been identified. Finally, the magnetic measurements suggest that an antiferromagnetic indirect exchange coupling takes place between the FM electrodes through the organic film.

In the past 30 years, magnetic research has been dominated by the question of how surfaces and interfaces influence the magnetic and transport properties of nanostructures, thin films and multilayers. The research has been particularly important in the magnetic recording industry where the giant magnetoresistance effect led to a new generation of storage devices including hand-held memories such as those found in the ipod. More recently, transfer of spin angular momentum across interfaces has opened a new field for high frequency applications.This book gives a comprehensive view of research at the forefront of these fields. The frontier is expanding through dynamic exchange between theory and experiment. Contributions have been chosen to reflect this, giving the reader a unified overview of the topic. - Addresses both theory and experiment that are vital for gaining an essential understanding of topics at the interface between magnetism and materials science - Chapters written by experts provide great insights into complex material - Discusses fundamental background material and state-of-the-art applications, serving as an indispensable guide for students and professionals at all levels of expertise - Stresses interdisciplinary aspects of the field, including physics, chemistry, nanocharacterization, and materials science - Combines basic materials with applications, thus widening the scope of the book and its readership

Materials Research in thin and ultrathin magnetic structures is a multidisciplinary field which heavily relies on state-of-the-art growth, characterization and theoretical approaches to build a comprehensive physical picture on how magnetic properties depend on interfacial structural issues, interlayer coupling and transport phenomena. Often in this field, the critical properties and characterization required necessitates knowledge of structural and magnetic phenomena extending over several atomic planes. Atomic controlled growth techniques are required and atomic sensitivity is needed from magnetic and structural probes. This critical knowledge is vital for device applications, providing the basis for the synergistic interactions that are predominant in this field of research. This volume is the definitive reference source for anyone interested in the latest advances and results of current experimental research in ultrathin film magnetism.

A fundamental need in wireless communication and modern computer processors is to fabricate faster, smaller, and lower power-consumption circuits. A promising approach is the utilization of spin waves, or rather, magnons in ferromagnetic films. Quantum confinement in ultra-thin films permits the coexistence of several exchange-dominated magnon modes with terahertz-range frequencies and sub-nanometer length scales. By means of spin-polarized electron energy loss spectroscopy (SPEELS), these exchange-dominated terahertz magnons are directly probed in ultra-thin cobalt films on Ir(001), Cu(001) and Pt(111) single crystal surfaces. The dispersion relation of the quantized magnon modes depends particularly on the interatomic exchange interaction in individual layers. By tuning the exchange interaction, modes with opposite group velocities, and thus an opposite propagation direction of the wave packets, can be generated. Ab initio theoretical calculations as well as an analytical Heisenberg model reveal a spatial localization of the modes at the surface, interior, and interface of the film that opens an experimental access to the layer-dependent magnetic properties. In itinerant ferromagnets like cobalt the magnetic properties depend sensitively on many-body correlation effects in the electronic structure. Here, it is shown for the first time that spin-dependent correlations lead to a pronounced renormalization of the energy of the highest magnon mode by up to 260 meV, explaining the significant overestimation of theoretically predicted magnon energies and interatomic exchange interaction found in literature.