Exploring Artificial Magnetism from Thin Films to Nanostructures

Surface, interface and bulk properties of artificially structured, new magnetic materials play a fundamental role in modern science and technology. From thin films to patterned magnetic nano-structures, these magnetic materials and systems can be utilized in many electrical and electronic devices. Using highly surface sensitive techniques, electron capture spectroscopy (ECS), angleand energy-resolved, spin-polarized ion-induced electron and Auger emission spectroscopy (SPEES) and scanning ion microscopy with polarization analysis (SIMPA), surface and interface magnetic order, shortand long-ranged magnetic order, magnetic anisotropy and critical behavior of ultra thin, patterned and continuous, macroand nano-magnetic systems are investigated. All systems are well characterized by using Auger electron spectroscopy, low and high energy electron diffraction and scanning tunneling microscopy. For several systems, surface and interface-enhanced magnetic order, 4d-ferromagnetism in two dimensions (2D), novel, non-universal surface critical behavior and magnetic anisotropies are found. Using SPEES, fundamental, element-specific information on layer-dependent electronic and magnetic properties of surfaces and interfaces is obtained. These findings are of paramount importance for a deeper and fundamental understanding of 2D ferromagnetism in thin films and nano-structures. SIMPA enables us to study and fabricate in situ nano-structured, 3D, 2D and 1D magnetic elements and systems to be used for ultra-high density magnetic data storage, read heads, magnetic sensors and spin-electronic devices. SIMPA allows for detailed observations of the internal structure of magnetic domains and domain walls by providing high resolution, spatiallyand spin-resolved maps of the orientation and magnitude of the surface electron spin polarization, which directly reveals the non-uniform behavior of the magnetization at the surface of magnetic domains. SIMPA is also utilized for studies on the dependence of magnetic domain structures on interlayer magnetic couplings as well as for studies on various magnetic vortex and antivortex configurations.