Nanoscale devices have taken center stage in both academic research and industry, bringing with them the need for fabrication, characterization, and understanding of tunable systems for device applications. Here I will discuss the fabrication, characterization, and future application of magnetic thin film systems, tunable hydrogen adsorption/desorption on transition metal thin films, and electrically tunable superconductivity in thin film YBCO devices. With the advancement of modern nanomagnetics and spintronics, the ability to control and tailor spin textures have become the focus of intense research interest. A spin-polarized low-energy electron microscope (SPLEEM) is used to both fabricate and characterize in-situ certain thin film magnetic systems, enabling studies including observing the nature of magnetic chirality within in-plane magnetized systems, as well as investigating induced perpendicular-magnetic anisotropy as a function of material topography. Similar techniques are used to fabricate and measure transition metal thin film systems and their hydrogen adsorption/desorption properties. Metals such as Ni, Pd, and Cs are added to the thin film surfaces to adjust the hydrogen adsorption/desorption characteristics without significantly affecting the physical or chemical properties of the film. Monolayer to submonolayer thicknesses of these metal overlayers were shown to result in H adsorption enhancement, adjustable H reversibility (adsorption/desorption ratio), H exclusion (adsorption suppression), and H trapping (desorption suppression), enabling a wide range of tunability over how H interacts with a thin film surface.

A detailed study of exchange-biased Fe/MnF2 bilayers using magneto-optical Kerr effect shows that the magnetization reversal occurs almost fully through domain wall nucleation and propagation for external fields parallel to the exchange-bias direction. For finite angles between bias and external field, the magnetization is aligned perpendicular to the cooling-field direction for a limited field range for decreasing fields. For external fields perpendicular to the bias direction, the magnetization aligns with the cooling-field direction for descending and ascending fields before fully reversing. The field range for which the magnetization is close to perpendicular to the external field can be estimated using a simple effective-field model.

The effects of rotating an applied field on the exchange anisotropy in Co/FeMn thin films have been investigated. When the applied field is initially along the cooling field direction, the longitudinal hysteresis loop has a maximum coercivity and the transverse hysteresis loop is flat, indicating that the exchange field is along the cooling field direction. When the applied field angle is rotated away and then restored to the original field cooling direction, the exchange anisotropy direction has changed. The rotation of the exchange field direction trails the applied field and is hysteretic. The rotational hysteresis of the exchange field direction is due to the weak anisotropy in thin FeMn layers and decreases with increasing FeMn thickness. (c) 2007 American Institute of Physics.