RESUMO
An in-plane spin-reorientation transition occurring during the growth of epitaxial Fe films on W(110) was studied in situ by using the nuclear resonant scattering of synchrotron radiation. The spin-reorientation transition originates at the Fe/W(110) interface and proceeds via a noncollinear spin structure resembling a planar domain wall that propagates towards the surface with increasing film thickness.
RESUMO
We report on the development of structural and magnetic order in epitaxially grown L10 FePt thin films. Upon annealing, the easy axis of magnetization changes from the out-of-plain into the in-plain direction. We found that the overall fraction of reoriented domains first increases but after certain time decreases before achieving a saturated state. The results are based on conversion electron Mössbauer spectroscopy studies and confirm Monte Carlo simulations in nano-layered FePt. We present a modified version of the Johnson-Mehl-Avrami (JMA) model adequately describing the experimental findings. Two dynamical processes, the first being a 2D-growth, dominate the initial state of sample annealing and the second being a 3D-growth, dominate the late stage close to saturation. From an Arrhenius plots of JMA coefficients for both processes we extracted the activation energies of the underlying dynamics which are 1.5(1) eV for disordering and 0.8(2) eV for ordering.
RESUMO
The in-plane density of phonon states of clean Fe(110) surface was measured separately for the first, second, and further atomic monolayers using nuclear inelastic scattering of synchrotron radiation. The results show that atoms of the first layer vibrate with frequencies significantly lower and amplitudes much larger than those in the bulk, and that vibrational spectra along two perpendicular in-surface directions are different. The vibrations of the second layer are already very close to those of the bulk. The good agreement of the experimental results and the first-principles calculations allows for detailed understanding of the observed phenomena.
RESUMO
Coronavirus-positive samples of faeces collected in an Austrian animal shelter from 12 cats and 10 dogs were analysed by reverse transcriptase-pcr with primers amplifying a segment of the M protein gene, and by sequence analysis. In addition, the samples were subjected to S gene typing, using primers that differentiated between feline coronavirus (fcov) types I and II. A phylogenetic analysis of the M gene sequences revealed not only clearly segregating canine coronavirus (ccov) in the dogs, typical ccov sequences and the recently described fcov-like ccov, but also at least two genetic clusters of fcov in the cats, one species-specific, the other more closely related to fcov-like ccov. The M gene sequences of these new feline strains had at most 88 per cent identity with the fcov-like ccov strain 259/01 and only up to 85 per cent with any fcov sequence available in GenBank. In the phylogenetic tree they occupy an intermediate position between feline and canine coronaviruses.
