13 research outputs found
Magnetic interactions in EuTe epitaxial layers and EuTe/PbTe superlattices
The magnetic properties of antiferromagnetic (AFM) EuTe epitaxial layers and
short period EuTe/PbTe superlattices (SLs), grown by molecular beam epitaxy on
(111) BaF substrates, were studied by magnetization and neutron diffraction
measurements. Considerable changes of the N\'eel temperature as a function of
the EuTe layer thickness as well as of the strain state were found. A mean
field model, taking into account the variation of the exchange constants with
the strain-induced lattice distortions, and the nearest neighbor environment of
a Eu atoms, was developed to explain the observed changes in wide
range of samples. Pronounced interlayer magnetic correlations have been
revealed by neutron diffraction in EuTe/PbTe SLs with PbTe spacer thickness up
to 60 \AA. The observed diffraction spectra were analyzed, in a kinematical
approximation, assuming partial interlayer correlations characterized by an
appropriate correlation parameter. The formation of interlayer correlations
between the AFM EuTe layers across the nonmagnetic PbTe spacer was explained
within a framework of a tight-binding model. In this model, the interlayer
coupling stems from the dependence of the total electronic energy of the
EuTe/PbTe SL on the spin configurations in adjacent EuTe layers. The influence
of the EuTe and PbTe layer thickness fluctuations, inherent in the epitaxial
growth process, on magnetic properties and interlayer coupling is discussed.Comment: 17 pages, 19 figures, accepted to PR
Effector CD8+CD45RO−CD27−T cells have signalling defects in patients with squamous cell carcinoma of the head and neck
Observing System Simulation Experiments in the Marmara Sea
Poster presented in Symposium for the legacy of Anna Trevisan in Bologna in Oct 201
Some applications of the reciprocity principle in experimental vibroacoustics
The principles of acoustic and vibroacoustic reciprocity are explained. Examples are then given of applications of acoustic reciprocity to the experimental analysis of sound radiation by various systems of interest to noise control engineers. The final part of the paper is devoted to a presentation of examples of the practical application of Lyamshev reciprocity to problems of identifying and quantifying sources of noise that operate in a variety of engineering systems