51 research outputs found
Histoire de la Hongrie médiévale: Des Angevins aux Habsbourgs
Écrit par trois des meilleurs historiens hongrois, le second tome de cette Histoire de la Hongrie médiévale montre comment s\u27est constituée l\u27identité hongroise dans les deux derniers siècles du Moyen Âge. Le royaume s\u27intègre alors dans la chrétienté latine et il connaît un développement rapide de la culture écrite. Ce livre est essentiel pour comprendre l\u27histoire de l\u27Europe du Centre-Est
Role of magnetic and orbital ordering at the metal-insulator transition in NdNiO3
Soft x-ray resonant scattering at the Ni L2,3 edges is used to test models of
magnetic and orbital-ordering below the metal-insulator transition in NdNiO3.
The large branching ratio of the L3 to L2 intensities of the (1/2,0,1/2)
reflection and the observed azimuthal angle and polarization dependence
originates from a non collinear magnetic structure. The absence of an orbital
signal and the non collinear magnetic structure show that the nickelates are
materials for which orbital ordering is absent at the metal-insulator
transition.Comment: 10 pages, 4 figures, Physical Review B rapid communication, to be
publishe
Prediction of huge X-ray Faraday rotation at the Gd N_4,5 threshold
X-ray absorption spectra in a wide energy range around the 4d-4f excitation
threshold of Gd were recorded by total electron yield from in-plane magnetized
Gd metal films. Matching the experimental spectra to tabulated absorption data
reveals unprecedented short light absorption lengths down to 3 nm. The
associated real parts of the refractive index for circularly polarized light
propagating parallel or antiparallel to the Gd magnetization, determined
through the Kramers-Kronig transformation, correspond to a magneto-optical
Faraday rotation of 0.7 degrees per atomic layer. This finding shall allow the
study of magnetic structure and magnetization dynamics of lanthanide elements
in nanosize systems and dilute alloys.Comment: 4 pages, 2 figures, final version resubmitted to Phys. Rev. B, Brief
Reports. Minor change
Charge transport and magnetization profile at the interface between a correlated metal and an antiferromagnetic insulator
A combination of spectroscopic probes was used to develop a detailed
experimental description of the transport and magnetic properties of
superlattices composed of the paramagnetic metal CaRuO and the
antiferromagnetic insulator CaMnO. The charge carrier density and Ru
valence state in the superlattices are not significantly different from those
of bulk CaRuO. The small charge transfer across the interface implied by
these observations confirms predictions derived from density functional
calculations. However, a ferromagnetic polarization due to canted Mn spins
penetrates 3-4 unit cells into CaMnO, far exceeding the corresponding
predictions. The discrepancy may indicate the formation of magnetic polarons at
the interface.Comment: 4 pages, 3 figure
Structure, morphology and magnetism of an ultra-thin [NiO/CoO]/PtCo bilayer with perpendicular exchange bias
Structural study of an amorphous NiZr2 alloy by anomalous wide angle X-ray scattering and Reverse Monte Carlo simulations
The local atomic structure of an amorphous NiZr2 alloy was investigated using
the anomalous wide-angle x-ray scattering (AWAXS), differential anomalous
scattering (DAS) and reverse Monte Carlo (RMC) simulations techniques. The
AWAXS measurements were performed at eight different incident photon energies,
including some close to the Ni and Zr K edges. From the measurements eight
total structure factor S(K,E) were derived. Using the AWAXS data four
differential structure factors DSFi(K,Em,En) were derived, two about the Ni and
Zr edges. The partial structure factors SNi-Ni(K), SNi-Zr(K) and SZr-Zr(K) were
estimated by using two different methods. First, the S(K,E) and DSFi(K,Em,En)
factors were combined and used in a matrix inversion process. Second, three
S(K,E) factors were used as input data in the RMC technique. The coordination
numbers and interatomic distances for the first neighbors extracted from the
partial structure factors obtained by these two methods show a good agreement.
By using the three-dimensional structure derived from the RMC simulations, the
bond-angle distributions were calculated and they suggest the presence of
distorted triangular-faced polyhedral units in the amorphous NiZr2 structure.
We have used the Warren chemical short-range order parameter to evaluate the
chemical short-range order for the amorphous NiZr2 alloy and for the NiZr2
compound. The calculated values show that the chemical short-range order found
in these two materials is similar to that found in a solid solution.Comment: Submitted to Phys. Rev. B, 8 figure
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