1,086 research outputs found
Inverse proximity effect at superconductor-ferromagnet interfaces: Evidence for induced triplet pairing in the superconductor
Considerable evidence for proximity-induced triplet superconductivity on the
ferromagnetic side of a superconductor-ferromagnet (S-F) interface now exists;
however, the corresponding effect on the superconductor side has hardly been
addressed. We have performed scanning tunneling spectroscopy measurements on
NbN superconducting thin films proximity coupled to the half-metallic
ferromagnet La2/3Ca1/3MnO3 (LCMO) as a function of magnetic field. We have
found that at zero and low applied magnetic fields the tunneling spectra on NbN
typically show an anomalous gap structure with suppressed coherence peaks and,
in some cases, a zero-bias conductance peak. As the field increases to the
magnetic saturation of LCMO where the magnetization is homogeneous, the spectra
become more BCS-like and the critical temperature of the NbN increases,
implying a reduced proximity effect. Our results therefore suggest that
triplet-pairing correlations are also induced in the S side of an S-F bilayer.Comment: 12 pages, 3 figure
Metrology and multipartite entanglement in measurement-induced phase transition
Measurement-induced phase transition arises from the competition between a
deterministic quantum evolution and a repeated measurement process. We explore
the measurement-induced phase transition through the Quantum Fisher Information
in two different metrological scenarios. We demonstrate through the scaling
behavior of the quantum Fisher information the transition of the multi-partite
entanglement across the phases. In analogy with standard quantum phase
transition, we reveal signature of a measurement-induced phase transition in
the non-analytic behaviour of the quantum Fisher information as the measurement
strength approaches the critical value. Our results offer novel insights into
the features of a quantum systems undergoing measurement-induced phase
transition and indicate potential avenues for further exploration in the field
of quantum physics
Electric control of superconducting transition through a spin-orbit coupled interface.
We demonstrate theoretically all-electric control of the superconducting transition temperature using a device comprised of a conventional superconductor, a ferromagnetic insulator, and semiconducting layers with intrinsic spin-orbit coupling. By using analytical calculations and numerical simulations, we show that the transition temperature of such a device can be controlled by electric gating which alters the ratio of Rashba to Dresselhaus spin-orbit coupling. The results offer a new pathway to control superconductivity in spintronic devices.J.L. and J.A.O. acknowledge funding via the “Outstanding Academic Fellows” programme at NTNU, the COST Action MP-1201 and the Research
Council of Norway Grant numbers 205591, 216700, and 240806. J.W.A.R. and A.D.B. acknowledge funding from the Leverhulme Trust (IN-2013-033), the Royal Society and the EPSRC through the Programme Grant
“Superconducting Spintronics” (EP/N017242/1), and the Doctoral Training Grant (NanoDTC EP/G037221/1
Thin film and surface preparation chamber for the low energy muons spectrometer
We have designed and constructed a thin film preparation chamber with base
pressure of ~mbar. Currently, the chamber is equipped with
two large area evaporators (a molecular evaporator and an electron-beam
evaporator), an ion sputtering gun, a thickness monitor and a substrate heater.
It is designed such that it can handle large area thin film samples with a
future possibility to transfer them in vacuum directly to the low energy muons
(LEM) spectrometer or to other advanced characterization facilities in the
Quantum Matter and Materials Center (QMMC) which will be constructed in 2024.
Initial commissioning of the chamber resulted in high quality, large area and
uniform molecular films of CuPc and TbPc on various substrate materials. We
present first results from low energy SR (LE-SR) measurements on
these films.Comment: 8 pages, 7 figures, muSR2020 conference proceeding
Dirac surface states, multiorbital dimerization and superconductivity in Nb- and Ta-based A15 compounds
Using first-principle calculations, we investigate the electronic,
topological and superconducting properties of NbX (X = Ge, Sn, Sb) and
TaY (Y = As, Sb, Bi) A15 compounds. We demonstrate that these compounds
host Dirac surface states which are related to a nontrivial Z topological
value. The spin-orbit coupling (SOC) splits the eightfold degenerate R point
close to the Fermi level enhancing the amplitude of the spin Hall conductance.
Indeed, despite the moderate spin-orbit of the Nb-compounds, a large spin Hall
effect is also obtained in NbGe and NbSn compounds. We show that the
Coulomb interaction opens the gap at the R point thus making more evident the
occurrence of Dirac surface states. We then investigate the superconducting
properties by determining the strength of the electron-phonon BCS coupling. The
evolution of the critical temperature is tracked down to the 2D limit
indicating a reduction of the transition temperature which mainly arises from
the suppression of the density of states at the Fermi level. Finally, we
propose a minimal tight-binding model based on three coupled
Su-Schrieffer-Heeger chains with t Ta- and Nb-orbitals reproducing the
spin-orbit splittings at the R point among the -bond bands in this class
of compounds. We separate the kinetic parameters in and -bonds,
in intradimer and interdimer hoppings and discuss their relevance for the
topological electronic structure. We point out that NbGe might represent a
Z topological metal with the highest superconducting temperature ever
recorded.Comment: 16 pages, 12 figures in main text, 3 figures in appendix, Paper
submitted to Physical Review
Microscopic theory of supercurrent suppression by gate-controlled surface depairing
Recently gate-mediated supercurrent suppression in superconducting
nano-bridges has been reported in many experiments. This could be either a
direct or an indirect gate effect. The microscopic understanding of this
observation is not clear till now. Using the quasiclassical Green's function
method, we show that a small concentration of magnetic impurities at the
surface of the bridges can significantly help to suppress superconductivity and
hence the supercurrent inside the systems while applying a gate field. This is
because the gate field can enhance the depairing through the exchange
interaction between the magnetic impurities at the surface and the
superconductor. We also obtain a \emph{symmetric} suppression of the
supercurrent with respect to the gate field, a signature of a direct gate
effect. Future experiments can verify our predictions by modifying the surface
with magnetic impurities
An Integrated Approach for Structural Health Monitoring and Damage Detection of Bridges: An Experimental Assessment
The issue of monitoring the structural condition of bridges is becoming a top priority worldwide. As is well known, any infrastructure undergoes a progressive deterioration of its structural conditions due to aging by normal service loads and environmental conditions. At the same time, it may suffer serious damages or collapse due to natural phenomena such as earthquakes or strong winds. For this reason, it is essential to rely on efficient and widespread monitoring techniques applied throughout the entire road network. This paper aims to introduce an integrated procedure for structural and material monitoring. With regard to structural monitoring, an innovative approach for monitoring based on Vehicle by Bridge Interaction (VBI) will be proposed. Furthermore, with regard to material monitoring, to evaluate concrete degradation, a non-invasive method based on the continuous monitoring of the pH, as well as chloride and sulfate ions concentration in the concrete, is presented
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Magnetotransport and magnetic properties of amorphous NdNi 5 thin films
Abstract: NdNi5 is an intermetallic compound with a bulk Curie temperature (TCurie) of 6–13 K. While existing studies have focused on NdNi5 crystals, amorphous thin-films of NdNi5 are potentially important since they would be magnetically soft without magnetocrystalline anisotropy, meaning that small external magnetic fields could reverse the direction of their magnetization. Here, we report NdNi5 thin-films with a thickness in the 5–200 nm range, deposited by DC magnetron sputtering onto Si(100). Films are amorphous with a weak temperature-dependent resistivity with values ranging between 150 and 300 μΩ cm. By means of noise spectroscopy, by analyzing the time-dependence of fluctuation-induced voltages, it is found that at low temperatures the resistance fluctuations are due to the Kondo effect. Volume magnetometry indicates TCurie=70 K with a magnetic coercive field of 30 mT at 5 K for a 125-nm-thick film. The results are promising for the development of Ferromagnet(F)/Superconductor(S)/Ferromagnet(F) pseudo spin-valve devices based on amorphous NdNi5 thin films
DG-CST (Disease Gene Conserved Sequence Tags), a database of human�mouse conserved elements associated to disease genes
The identification and study of evolutionarily conserved genomic sequences that surround disease-related genes is a valuable tool to gain insight into the functional role of these genes and to better elucidate the pathogenetic mechanisms of disease. We created the DG-CST (Disease Gene Conserved Sequence Tags) database for the identification and detailed annotation of human–mouse conserved genomic sequences that are localized within or in the vicinity of human disease-related genes. CSTs are defined as sequences that show at least 70% identity between human and mouse over a length of at least 100 bp. The database contains CST data relative to over 1088 genes responsible for monogenetic human genetic diseases or involved in the susceptibility to multifactorial/polygenic diseases. DG-CST is accessible via the internet at http://dgcst.ceinge.unina.it/ and may be searched using both simple and complex queries. A graphic browser allows direct visualization of the CSTs and related annotations within the context of the relative gene and its transcripts
DG-CST (Disease Gene Conserved Sequence Tags), a database of human–mouse conserved elements associated to disease genes
The identification and study of evolutionarily conserved genomic sequences that surround disease-related genes is a valuable tool to gain insight into the functional role of these genes and to better elucidate the pathogenetic mechanisms of disease. We created the DG-CST (Disease Gene Conserved Sequence Tags) database for the identification and detailed annotation of human–mouse conserved genomic sequences that are localized within or in the vicinity of human disease-related genes. CSTs are defined as sequences that show at least 70% identity between human and mouse over a length of at least 100 bp. The database contains CST data relative to over 1088 genes responsible for monogenetic human genetic diseases or involved in the susceptibility to multifactorial/polygenic diseases. DG-CST is accessible via the internet at http://dgcst.ceinge.unina.it/ and may be searched using both simple and complex queries. A graphic browser allows direct visualization of the CSTs and related annotations within the context of the relative gene and its transcripts
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