23 research outputs found
Reentrant superconductivity in superconductor/ferromagnetic-alloy bilayers
We studied the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) like state
establishing due to the proximity effect in superconducting Nb/Cu41Ni59
bilayers. Using a special wedge-type deposition technique, series of 20-35
samples could be fabricated by magnetron sputtering during one run. The layer
thickness of only a few nanometers, the composition of the alloy, and the
quality of interfaces were controlled by Rutherford backscattering
spectrometry, high resolution transmission electron microscopy, and Auger
spectroscopy. The magnetic properties of the ferromagnetic alloy layer were
characterized with superconducting quantum interference device (SQUID)
magnetometry. These studies yield precise information about the thickness, and
demonstrate the homogeneity of the alloy composition and magnetic properties
along the sample series. The dependencies of the critical temperature on the Nb
and Cu41Ni59 layer thickness, Tc(dS) and Tc(dF), were investigated for constant
thickness dF of the magnetic alloy layer and dS of the superconducting layer,
respectively. All types of non-monotonic behaviors of Tc versus dF predicted by
the theory could be realized experimentally: from reentrant superconducting
behavior with a broad extinction region to a slight suppression of
superconductivity with a shallow minimum. Even a double extinction of
superconductivity was observed, giving evidence for the multiple reentrant
behavior predicted by theory. All critical temperature curves were fitted with
suitable sets of parameters. Then, Tc(dF) diagrams of a hypothetical F/S/F
spin-switch core structure were calculated using these parameters. Finally,
superconducting spin-switch fabrication issues are discussed in detail in view
of the achieved results.Comment: 34 pages, 9 figure
COUP-TFI modifies CXCL12 and CXCR4 expression by activating EGF signaling and stimulates breast cancer cell migration
The Spectrometer Telescope for Imaging X-rays (STIX) on Solar Orbiter
The Spectrometer/Telescope for Imaging X-rays (STIX) is one of the 10
instruments on-board the scientific payload of ESA's Solar Orbiter mission.
STIX provides hard X-ray imaging spectroscopy in the 4-150~keV energy range,
observing hard X-ray bremsstrahlung emission from the Sun. These observations
provide diagnostics of the hottest thermal plasmas (10~MK) and information
on the non-thermal energetic electrons accelerated above 10~keV during solar
flares. STIX has a spectral resolution of 1~keV, and employs the use of
in-direct bi-grid Fourier imaging to spatially locate hard X-ray emission.
Given that STIX provides critical information about accelerated electrons at
the Sun through hard X-ray diagnostics, it is a powerful contribution to the
Solar Orbiter suite and has a significant role to explore the dynamics of solar
inputs to the heliosphere. This chapter describes the STIX instrument, its
design, objectives, first observations and outlines the new perspectives STIX
provides over the mission lifetime of Solar Orbiter.Comment: 18 pages, 11 figures, Book Chapter for Handbook of X-ray and
Gamma-ray Astrophysic