Ion-beam sputtering has been used to prepare Fe/Si multilayers on a variety of substrates and over a wide range of temperatures. Small-angle x-ray diffraction and transmission electron microscopy experiments show that the layers are heavily intermixed although a composition gradient is maintained.When the spacer layer is an amorphous iron silicide, the magnetic properties of the multilayers are similar to those of bulk Fe. When the spacer layer is a crystalline silicide with the B2 or DO 3 structure, the multilayers show antiferromagnetic interlayer coupling like that observed in ferromagnet/paramagnet multilayers such as Fe/Cr and Co/Cu. Depending on the substrate type and the growth temperature, the multilayers grow in either the (011) or (001) 75.50. Bb,68.65.+g,81.15.Cd,75.30.E

Magnetization reversal processes in epitaxial NiO/NiFe bilayers were studied using the magneto-optic indicator film technique. The influence of dislocations on these processes was determined. Remagnetization parallel to the unidirectional anisotropy axis proceeds by domain nucleation and growth, with nucleation center activity being asymmetric with respect to the applied field sign. Magnetization reversal in the hard axis direction occurs by incoherent rotation. The enhanced coercivity and asymmetric nucleation can be explained by taking into account domain wall behavior in the antiferromagnetic layer.

Structural properties of single-phase films of κ-In 2 Se 3 and γ-In 2 Se 3 were investigated.Both films were polycrystalline but their microstructure differed considerably. The alattice parameter of κ-In 2 Se 3 has been measured. Comparison between these two materials indicates that κ-In 2 Se 3 has a significantly larger unit cell (∆c = 2.5 ± 0.2 % and ∆a = 13.5 ± 0.5 %) and a structure more similar to the α-phase of In 2 Se 3 . a)

We report element-specific magnetic hysteresis measurements on heteromagnetic materials. Dramatically different Fe and Co hysteresis curves of Fe/Cu/Co trilayers were obtained by recording the magnetic circular dichroism at their respective L3 white lines as a function of applied magnetic field. The data resolve the complicated hysteresis curves, observed by conventional magnetometry, and determine the individual magnetic moments for the Fe and Co layers. Fine hysteresis features, imperceptible in the conventional curves, were also observed, demonstrating a new and powerful means for studying heteromagnetic multilayer systems.

We observe surface stress changes in response to thermal dehybridization, or melting, of double-stranded DNA (dsDNA) oligonucleotides that are grafted on one side of a microcantilever beam. Changes in surface stress occur when one complementary DNA strand melts and diffuses away from the other, resulting in alterations of the electrostatic, counterionic, and hydration interaction forces between the remaining neighboring surface-grafted DNA molecules. We have been able to distinguish changes in the melting temperature of dsDNA as a function of salt concentration and oligomer length. This technique also highlights differences between surface immobilized and solution DNA melting dynamics, which allows us to better understand the stability of DNA on surfaces. The transduction of phase transitions into a mechanical signal is ubiquitous for DNA, making cantilever-based detection a widely useful and complementary alternative to calorimetric and fluorescence measurements.