Grazing-incidence Ar+ ion sputtering has been used to produce nanoscale ripples on the surface of the Fe∕Mg(001) system. This way, a uniaxial anisotropy with both controllable strength and orientation can be superimposed on top of the cubic anisotropy, resulting in Fe∕MgO(001) films with unusual anisotropy symmetry. By combining longitudinal and transverse Kerr-effect measurements, different switching processes are revealed. Depending on the orientation of the external magnetic field, one-jump, two-jump, and “reverse” two-jump magnetization reversals can be observed. A simple model, which takes into account the relevant anisotropy energies, is developed to explain the experimentally observed switching fields and to evaluate the domain wall pinning energies of the sputtered sample.

We investigate the magnetization reversal in Fe/MgO͑001͒ films with fourfold in-plane magnetic anisotropy and an additional uniaxial anisotropy whose orientation and strength are altered using different growth geometries and postgrowth treatments. The previously adopted mechanism of 180°domain-wall nucleation clearly fails to explain the observed 180°magnetization reversal in Fe/MgO͑001͒ films. We introduce a reversal mechanism with two successive domain-wall nucleations to consistently predict the switching fields of Fe/ MgO͑001͒ films for all field orientations with one set of values for domain-wall nucleation energies and uniaxial anisotropy.

In this work, an in-depth growth study with organic vapor phase deposition of the n-type semiconductor N, 4,9, ) is presented. The organic vapor phase deposition technique allows independent control of more parameters than traditional vapor thermal evaporation, namely, not only deposition flux and substrate temperature but also chamber pressure can be changed. We study the influence of these parameters on the morphology and microstructure of PTCDI-C 13 thin films, and correlate them with electrical properties. Films of PTCDI-C 13 on SiO 2 surfaces modified with poly-(Rmethylstyrene) exhibit Stranski-Krastanov growth. Upon increasing deposition flux, the resulting surface morphology changes from rough films, characterized by needle growth, to smoother films consisting of small, uniform grains. Notably, increasing the pressure shifts this morphology transition toward lower deposition fluxes. All X-ray reflectivity measurements are indicative of PTCDI-C 13 molecules assembling in well-ordered π-stacks parallel to the substrate. This creates the opportunity to grow PTCDI-C 13 films at conditions maximizing deposition throughput and efficiency, while maintaining the structural and thus electrical quality of the PTCDI-C 13 thin films. Electron mobilities up to 0.1 cm 2 /(Vs) have been demonstrated for a deposition rate of 6.7 Å/s, showing that organic vapor phase deposition is a high-throughput deposition technique for perylene diimide n-type organic semiconductors.

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We have studied surface morphology and magnetic properties of Fe/MgO(001) films deposited at an angle varying between 0 o and 60 o with respect to the surface normal and with azimuth along the Fe [010] or the Fe[110] direction. Due to shadowing, elongated grains appear on the film surface for deposition at sufficiently large angle. X-ray reflectivity reveals that, depending on the azimuthal direction, films become either rougher or smoother for oblique deposition. For deposition along Fe[010] the pronounced uniaxial magnetic anisotropy (UMA) results in the occurrence of "reversed" two-step and of three-step hysteresis loops. For deposition along Fe[110] the growth-induced UMA is much weaker, causing a small rotation of the easy axes.Magnetic anisotropy of epitaxial films and its relationship to surface morphology have attracted much attention in recent years [1]. Both film properties are intimately related to the molecular beam epitaxy (MBE) deposition process. Oblique incidence deposition results via a self-shadowing effect [2,3] in the formation of grains in the plane of the film that are elongated perpendicular to the incident flux direction and with aspect ratio increasing at larger deposition angle with respect to the surface normal [4]. Consequently, an in-plane uniaxial magnetic anisotropy (UMA) with easy axis perpendicular to the incident flux direction is induced during growth of the magnetic films [4,5,6]. UMA was found to play an important role in determining the magnetization reversal in thin films of cubic systems [7,8]. Depending on the strength and orientation of the UMA, hysteresis curves with one, two and three steps are observed in various films at different field orientation. The appearance of the steps can be explained in terms of nucleation and propagation of domain walls (DWs) [8,9]. Consequently, understanding the influence of oblique incidence growth is very important because of its ability to control both magnetic anisotropy and surface morphology [10,11,12].Although shadowing effects have been studied in many magnetic systems, including Fe on MgO(001) [13] and Co on Cu(001) [14], the plane of oblique incidence was always kept parallel to the in-plane cubic easy axes of the magnetic layers. Here, we report on the influence of oblique deposition on the surface morphology and magnetic properties of Fe/MgO(001) films for deposition azimuth both along the Fe Fig. 1(c)). The elongated grains are believed to result from a redistribution of the incident flux due long-range attractive forces [15,16]. During evaporation the incident Fe atoms arrive preferentially on top of already formed grains rather than behind these grains. This shadowing effect is also observed for film deposition at 60 o with azimuth along [110]. The Fe grains on the surface are rhombic in shape with typical length of 15 nm and typical width of 6 nm (see Fig. 1(d)). Based on the STM images we conclude that the self-shadowing effect can be neglected for a deposition angle below 30 o . Moreover, the self-shadowing effect is...