Using a combination of synchrotron radiation based magnetic imaging and high-resolution transmission electron microscopy we reveal systematic correlations between the magnetic switching field and the internal nanoscale structure of individual islands in bit patterned media fabricated by Co/Pd-multilayer deposition onto pre-patterned substrates. We find that misaligned grains at the island periphery are a common feature independent of the island switching field, while irregular island shapes and misaligned grains specifically extending into the center of an island are systematically correlated with a reduced island reversal field.

In a molecular-beam-epitaxy (MBE) chamber, epitaxial growth of all the silicides existing in the lowtemperature portion of the iron-silicon phase diagram Ie.g., bcc Fe {+Si),Fesi, and the semiconducting silicide P-FeSi2] was achieved on the (111)face of silicon by deposition of pure iron onto a heated silicon substrate. The epitaxial growth has been characterized by means of in situ reAection high-energy electron diffraction (RHEED), ultraviolet photoemission spectroscopy, and x-ray photoemission spectroscopy. A strained phase, s-FeSi2, has been clearly identified and shown to be metallic. This phase could be stabilized by the anisotropic elastic field induced by the epitaxy on the silicon (111)face which prevents a solid-state Jahn-Teller effect from distorting the cubic FeSi, structure and opening the gap. Also during the growth, dynamical transitions between the different epitaxial phases have been observed at definite thicknesses (typically in the range 10 -20 A): (i) At the temperature of the silicon substrate T =350'C, strained s-Fesi2~Fesi; (ii) at T =400 C, strained s-Fesiz~P-FeSi2. In our work such dynamical transitions are experimentally observed in situ during the growth. This shows that the use of a MBE chamber and in situ RHEED are very powerful techniques for studying and controlling metallurgical transformations on nanorneter scale in real time. We interpret these dynamical transitions as being due to the combination of two effects: a change in the silicon atomic flux coming from the silicon substrate to the surface and the relaxation of the strained phase.

GaSe, a layered semiconductor, may be grown on the Si͑111͒ surface by molecular beam epitaxy. The crystalline quality is relatively good, in the sense that the MeV 4 He ion minimum channeling yield (ϳ30%) is as low as that of state-of-the-art bulk material, and the interface is atomically abrupt. The initial film deposits are epitaxial islands, and subsequent growth is in the Frank-van der Merwe mode. With the islands already relaxed at the nucleation stage and coalescing to essentially uniform coverage with the first monolayer of deposition, GaSe on Si͑111͒ provides an example of van der Waals epitaxy. However, it is difficult to understand how epitaxy ͑crystallographic alignment with the substrate͒ can occur in such a case, where the film is incommensurate starting from the initial nuclei. A mechanism for alignment of the islands is proposed: they are aligned with the silicon substrate through the influence of dangling bonds at their perimeter, being ''quasicommensurate '' by virtue of their small lateral size. Although discommensurate regions are created as the islands grow laterally, there is simply no change in their orientation. © 1997 American Institute of Physics. ͓S0021-8979͑97͒05011-1͔