This first focused treatment on a hot topic highlights fundamental aspects as well as technological applications arising from a fascinating area of condensed matter physics. The editors have excellent track records and, in light of the broadness of the topic, retain the focus on antiferromagnetic oxides. They thus cover such topics as dichroism in x-ray absorption, non-magnetic substrates, exchange bias, ferromagnetic-antiferromagnetic interface coupling and oxide multilayers, as well as imaging using soft x-ray microscopy. The result is a very timely monograph for solid state physicists and chemists, materials scientists, electrical engineers, physicists in industry, physical laboratory technicians, and suppliers of sensors.

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.

In this dissertation, we investigate the stabilization and dynamics of chiral domain walls and skyrmions in several ferromagnet/heavy metal thin-film multilayers. In each material system, the ferromagnet/heavy metal interfaces were engineered to give rise to an interfacial Dzyaloshinskii-Moriya interaction (iDMI)--a spin-orbit coupling mediated effect known to promote the formation of chiral magnetic textures. Throughout several comprehensive studies (presented herein as separate chapters), we explore the stabilization and dynamics of skyrmions in three distinct types of material systems: Thin-films close to experiencing a spin-reorientation transition, ultrathin films with low ferromagnetic exchange and high perpendicular magnetic anisotropy, and thick multilayers with large perpendicular magnetic anisotropy. Through experimental and theoretical studies, we explore the processes by which skyrmions can be created and moved in response to both quasi-static and transient electrical currents, magnetic fields, and temperature changes. In all cases, the systematic variation of material properties and experimental conditions to better understand and control the mechanisms by which skyrmions are stabilized is a key underlying theme. In another thrust, we have studied the field-driven dynamics of chiral domain walls and have characterized a new effect in which magnetic stripe domains with chiral domain walls unidirectionally expand in response to applied magnetic fields, with growth symmetries that cannot be understood from the static energy frameworks typically employed to understand the impact of the interfacial Dzyaloshinskii-Moriya interaction in thin-film systems. Using analytical models, we have found that the in-plane torques generated by perpendicular magnetic fields stabilize steady-state domain wall magnetization profiles that are highly asymmetric in elastic energy, resulting in abnormal growth behaviors that are in line with the experimental findings. Building on this understanding of the field-driven dynamics of stripe domains, we expand this understanding to the growth directionalities observed when stripe domain motion is induced by spin-orbit torque.

Magnetic properties of (111)-textured SAF/Cu/FL multilayer film structures were optimized by varying individual layer thickness and sputtering conditions. The SAF is a synthetic antiferromagnet consisting of Co/Ni multilayers coupled antiferromagnetically across a Ru spacer layer, and the FL is a free layer consisting of a single Co/Ni multilayer. The Co and Ni thicknesses were varied to obtain larger perpendicular magnetic anisotropy. The perpendicular magnetic anisotropy, saturation magnetization, damping and zero-frequency line broadening of the Co/Ni multilayers strongly depend on the number of bilayers. With increasing Cu seed-layer thickness, the texture of the Co/Ni multilayers improves while the grain size and film roughness increase. The increase in grain size results in the reduction of the direct exchange coupling between magnetic grains, which enhances the coercivity of the SAF and the FL. Experimentally measured coercivities of the SAF and FL are compared with calculations obtained from a coherent rotation model. The effect of the role of the Co/Cu interface in the magnetoresistance, is also discussed. Spin-transfer-torque induced switching is investigated in 200 nm diameter circularly shaped, perpendicular magnetized nanopillars. The SAF layer is used as a reference layer to minimize the dipolar field on the free layer. The use of Pt and Pd was avoided to lower the spin-orbit scattering in magnetic layers and intrinsic damping in the free layer, and therefore, reduce the critical current required for spin-transfer-torque switching. In zero magnetic field the critical current required to switch the free layer from the parallel to antiparallel (antiparallel to parallel) alignment is 5.2 mA (4.9 mA). Given the volume of the free layer, VFL = 1.01×10-22 m3, the switching efficiency, Ic/(VFL m0Hc), is 5.28×1020 A/Tm3, twice as efficient as any previously reported device with a similar structure. Variation in perpendicular magnetic anisotropy of (111) textured Au/N×[Co/Ni]/Au films as a function of number of bilayer repeats N is studied. The experimental measurements show that the perpendicular magnetic anisotropy of Co/Ni multilayers first increases with N for N ≤ 10 and then moderately decreases for N> 10. The model we propose reveals that the decrease of the anisotropy for N 10 is predominantly due to the reduction in the magnetoelastic and magnetocrystalline anisotropies. A moderate decrease in the perpendicular magnetic anisotropy for N 10 is due to the reduction in the magnetocrystalline and the surface anisotropies.