A domain wall in a ferromagnetic material is a boundary between differently magnetized regions, and its motion provides a convenient scheme to control the magnetization state of the material. Domain walls can be confined and moved along nanostrips of magnetic thin films, which are proposed platforms for next generations of solid-state magnetic memory-storage and logic devices. In these devices, domain walls must be moved by electric current, rather than by magnetic field, to achieve scalability and lower-power operation. Recent studies have reported efficient domain-wall motion driven by current in out-of-plane magnetized multilayer films with strong spin-orbit coupling. In particular, extraordinary current-driven domain-wall motion has been observed in atomically-thin ferromagnets sandwiched between a nonmagnetic heavy metal and an insulator. Through experimental studies on various sputtered magnetic multilayers, we elucidate the mechanism of such anomalous domain-wall dynamics. We show that conventional current-induced spin-transfer torques, which drive domain walls in thicker films, are negligible in ultrathin ferromagnets. We also show that the Rashba field, often reported in materials with strong spin-orbit coupling, does not contribute to the observed efficient domain-wall motion. The anomalous dynamics instead emerges from the spin Hall effect: a charge current in the nonmagnetic heavy metal generates a spin current, which exerts a torque on spins in the adjacent ferromagnet. This spin Hall torque drives domain walls forward if the domain-wall spins are parallel to the nanostrip axis with a fixed chirality. We reveal that the Dzyaloshinskii-Moriya interaction, arising from spin-orbit coupling and asymmetric interfaces, stabilizes homochiral domain walls in ultrathin ferromagnets. Our findings not only provide a route to bolster current-driven domain-wall dynamics, but also enable new chiral magnetic textures in magnetic heterostructures for device applications.

Recent advances in thin film growth technology to create complex oxide heterostructures with atomic-level precision have enabled the discovery of a wide range of novel physical phenomena at engineered interfaces. These phenomena arise from the complex interactions between the lattice, charge, spin, and orbital degrees of freedom that are highly sensitive to external stimuli such as strain, chemical doping, and electric and magnetic fields. Among these complex oxide systems, heterostructures consisting of layers with competing magnetic characteristics have attracted great attention from a fundamental perspective as well as for their potential applications in magnetic sensors, magnetic random access memory, and future spintronics devices. One of the fundamental building blocks of such devices is the exchange-bias (EB) effect which is typically associated with interfacial exchange interactions between a ferromagnetic (FM) and an antiferromagnetic (AFM) material. A similar effect has also been observed at interfaces between hard and soft FM layers, where the hard (soft) layer possesses high (low) coercivity and low (high) saturation magnetization. In analogy to AFM/FM interfaces, the biasing effect at FM/FM interfaces originates from the magnetic unidirectional anisotropy induced by the exchange interactions between the hard and soft FM layers. The exchange interactions in complex oxide heterostructures consisting of La0.7Sr0.3MnO3 (LSMO) and La0.7Sr0.3CoO3 (LSCO) layers were systematically studied. LSMO is a soft FM metal that shows coincident FM-to-paramagnetic (PM) and metal-to-insulator transitions at ~ 360 K in its bulk form. LSCO is a hard FM material and is known to show magneto-electronic phase separation (MEPS), where FM/metallic clusters are embedded in a non-magnetic/insulating matrix. Synchrotron radiation based resonant x-ray reflectivity, soft x-ray magnetic spectroscopy, and bulk magnetometry were used to investigate the magnetic and electronic structure of the LSMO/LSCO heterostructures. It was found that a 6 nm LSMO/ 6 nm LSCO heterostructure displayed unconventional magnetic switching behavior, which deviated from conventional metallic FM/FM systems in that reversible switching occurred not only within the soft LSMO layer but was also accompanied by the switching of a thin interfacial LSCO layer. This unique magnetic switching behavior was strongly dependent on the thickness of the LSCO layer. Soft x-ray magnetic spectroscopy allowed us to develop a physical picture where a form of MEPS occurred vertically through the LSCO film thickness and was driven by the competition between two different interfacial effects at the LSMO/LSCO and the LSCO/substrate interfaces. These findings provide further evidence of the high tunability of magnetic properties in complex oxide heterostructures through interface engineering. In addition, domain wall injection and propagation in LSMO nanowires was investigated to ascertain its potential for magnetic memory device applications. A nanofabrication process combining e-beam lithography and ion implantation was used to pattern LSMO thin films. With the help of state-of-the-art x-ray photoemission electron microscopy, the magnetic domain patterns in various nanowire structures were directly imaged and magnetic field-assisted domain wall injection and propagation processes were monitored. Detailed domain wall structures were identified and the range of magnetic fields needed to move the domain walls were determined. It was found that the domain wall structures in LSMO nanostructures differed from the ones found in permalloy (Ni81Fe19) and were dependent on the crystallographic orientation of the nanowires. Furthermore, electrical transport studies on LSMO nanowires were performed. Pd metal was identified as the ideal contact metal that showed Ohmic behavior and low contact resistance. Resistance measurements as a function of temperature and magnetic field indicated that the LSMO nanowires preserved the electrical properties of the LSMO thin film. These results provide insight on the effect of nanostructuring on the magnetic and electrical properties of complex oxide nanowires, and illustrate the possibility of their application in magnetic memory devices.

Technological evolution and revolution are both driven by the discovery of new functionalities, new materials and the design of yet smaller, faster, and more energy-efficient components. Progress is being made at a breathtaking pace, stimulated by the rapidly growing demand for more powerful and readily available information technology. High-speed internet and data-streaming, home automation, tablets and smartphones are now "necessities" for our everyday lives. Consumer expectations for progressively more data storage and exchange appear to be insatiable. Oxide electronics is a promising and relatively new field that has the potential to trigger major advances in information technology. Oxide interfaces are particularly intriguing. Here, low local symmetry combined with an increased susceptibility to external fields leads to unusual physical properties distinct from those of the homogeneous bulk. In this context, ferroic domain walls have attracted recent attention as a completely new type of oxide interface. In addition to their functional properties, such walls are spatially mobile and can be created, moved, and erased on demand. This unique degree of flexibility enables domain walls to take an active role in future devices and hold a great potential as multifunctional 2D systems for nanoelectronics. With domain walls as reconfigurable electronic 2D components, a new generation of adaptive nano-technology and flexible circuitry becomes possible, that can be altered and upgraded throughout the lifetime of the device. Thus, what started out as fundamental research, at the limit of accessibility, is finally maturing into a promising concept for next-generation technology.

The MRS Symposium Proceeding series is an internationally recognised reference suitable for researchers and practitioners.

This volume contains papers presented at the IUTAM Symposium on Bubble Dynamics and Interface Phenomena held at the University of Birmingham from 6-9 September 1993. In many respects it follows on a decade later from the very successful IUTAM Symposium held at CALTECH in June 1981 on the Mechanics and physics of bubbles in liquids which was organised by the late Milton Plesset and Leen van Wijngaarden. The intervening period has seen major development with both experiment and theory. On the experimental side there have been ad vances with very high speed photography and data recording that provide detailed information on fluid and interface motion. Major developments in both computer hardware and software have also led to extensive improvement in our understand ing of bubble and interface dynamics although development is still limited by the sheer complexity of the laminar and turbulent flow regimes often associated with bubbly flows. The symposium attracts wide and extensive interest from engineers, physical, chemical, biological and medical scientists and applied mathematicians. The sci entific committee sought to achieve a balance between theory and experiment over a range of fields in bubble dynamics and interface phenomena. It was our intention to emphasise both the breadth and recent developments in these various fields and to encourage cross-fertilisation of ideas on both experimental techniques and theo retical developments. The programme, and the proceedings recorded herein, cover bubble dynamics, sound and wave propagation, bubbles in flow, sonoluminescence, acoustic cavitation, underwater explosions, bursting bubbles and ESWL.

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.

Magnetic skyrmions are particle-like objects described by localized solutions of non-linear partial differential equations. Up until a few decades ago, it was believed that magnetic skyrmions only existed in condensed matter as short-term excitations that would quickly collapse into linear singularities. The contrary was proven theoretically in 1989 and evidentially in 2009. It is now known that skyrmions can exist as long-living metastable configurations in low-symmetry condensed matter systems with broken mirror symmetry, increasing the potential applications possible. Magnetic Skyrmions and their Applications delves into the fundamental principles and most recent research and developments surrounding these unique magnetic particles. Despite achievements in the synthesis of systems stabilizing chiral magnetic skyrmions and the variety of experimental investigations and numerical calculations, there have not been many summaries of the fundamental physical principles governing magnetic skyrmions or integrating those concepts with methods of detection, characterization and potential applications. Magnetic Skyrmions and their Applications delivers a coherent, state-of-the-art discussion on the current knowledge and potential applications of magnetic skyrmions in magnetic materials and device applications. First the book reviews key concepts such as topology, magnetism and materials for magnetic skyrmions. Then, charactization methods, physical mechanisms, and emerging applications are discussed. Covers background knowledge and details the basic principles of magnetic skyrmions, including materials, characterization, statics and dynamics Reviews materials for skyrmion stabilization including bulk materials and interface-dominated multilayer materials Describes both well-known and unconventional applications of magnetic skyrmions, such as memristors and reservoir computing